User equipment

ABSTRACT

The present invention provides communication control methods relating to control signal management, a user equipment (UE), and a network node. The method includes transmitting a first initial Protocol Data Unit (PDU) session establishment request message containing a request type field to the network node to establish a first PDU session with a Data Network Name (DNN) and a Single Network Slice Selection Assistance Information (S-NSSAI); receiving a PDU session establishment reject message; setting a request type field contained within a second initial PDU session establishment request message to initial request to establish a second PDU session based on a cause value of the PDU session establishment reject message indicating the first PDU session does not exist; and transmitting the second initial PDU session establishment request message to the network node to establish the second PDU session.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority based on Japanese PatentApplication No.

2018-189949 filed on Oct. 5, 2018, the content of which is incorporatedherein by reference.

FIELD

The present invention relates to a user equipment (UE).

BACKGROUND

The 3GPP (3rd Generation Partnership Project), undertaking activitiesfor standardizing recent mobile communication systems has studied asystem architecture for LTE (Long Term Evolution), i.e. SAE (SystemArchitecture Evolution). The 3GPP has been standardizing an EPS (EvolvedPacket System) as a communication system for implementing all IP(Internet Protocol). In addition, a core network constituting an EPS isreferred to as an EPC (Evolved Packet Core).

In addition, the 3GPP recently has been studying a next-generationcommunication technology and a system architecture for 5G (5thGeneration) mobile communication systems, i.e., next-generation mobilecommunication systems, and especially, the 3GPP has been standardizing a5GS (5G System) as a system for implementing 5G mobile communicationsystems (see NPL 1 and NPL 2). In the 5GS, technical problemsattributable to connection of various terminals to a cellular networkare extracted to standardize solutions.

Requirements for the solutions include, for example, optimization anddiversification of communication procedures for supporting continuousmobile communication services depending on a terminal that supportsvarious and diverse access networks, optimization of a systemarchitecture according to the optimization and diversification of thecommunication procedures, and the like.

PRIOR ART LITERATURE Non-Patent Literature

-   Non-Patent Document 1: 3GPP TS 23.501 v15.0.0; 3rd Generation    Partnership Project; Technical Specification Group Services and    System Aspects; System Architecture for the 5G System; Stage 2    (Release 15)-   Non-Patent Document 2: 3GPP TS 23.502 v15.0.0; 3rd Generation    Partnership Project; Technical Specification Group Services and    System Aspects; Procedures for the 5G System; Stage 2 (Release 15)

SUMMARY Technical Problem

In the 5GS, in addition to a configuration that provides a functionequivalent to a congestion management, a control signal management basedon causes other than the congestion management is being studied (see NPL1 and NPL 2).

However, operation processes related to the session management of aterminal receiving a cause, which is notified by the network to theterminal in order to apply a control signal management based on thecause other than a congestion management, is not clarified. In addition,like the congestion management, a back-off timer management process inthe case that a back-off timer is notified to the terminal is notclarified.

One aspect of the present invention can be achieved in view of theforegoing circumstances, and an objective of the present invention is toprovide a configuration and a communication control method forimplementing a control signal management process based on a cause otherthan a congestion management.

Solution to Problem

A user equipment of the present invention comprises a transmission unit,wherein when a received 5GSM cause value indicates that a PDU sessiondoes not exist, the transmission unit transmits an initial PDU sessionestablishment request message.

A user equipment of the present invention comprises a reception unit anda control unit, wherein when the reception unit receives a 5GSM causevalue, which indicates that a request is rejected or unspecified, and atimer, the control unit activates a back-off timer for a combination ofPLMN, DNN and S-NSSAI based on the 5GSM cause value in a case that the5GSM cause value indicates a cause value other than another cause valuerelated to congestion management.

A user equipment of the present invention comprises a reception unit anda control unit, wherein when the reception unit receives a 5GSM causevalue and a timer, the control unit activates a back-off timer for acombination of PLMN, DNN and S-NSSAI based on the 5GSM cause value in acase that the 5GSM cause value indicates a cause value other thananother cause value related to congestion management.

A user equipment of the present invention comprises a control unit,wherein when a received 5GSM cause value indicates a cause value otherthan congestion management, the control unit ignores a received back-offtimer.

Invention Effect

According to the above-described configuration, a terminal apparatusconstituting a 5GS and an apparatus within a core network can performmanagement processes such as congestion managements initiated by theterminal apparatus and by a network for each network slice and/or a DNNor an APN.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a schematic diagram of a mobilecommunication system.

FIG. 2 is a diagram illustrating an example of a configuration of anaccess network in a mobile communication system.

FIG. 3 is a diagram illustrating an example of a configuration and thelike of a core network_A in a mobile communication system.

FIG. 4 is a diagram illustrating an example of a configuration of a corenetwork in a mobile communication system.

FIG. 5 is a diagram illustrating an apparatus configuration of a UE.

FIG. 6 is a diagram illustrating an apparatus configuration of an eNB/NRnode.

FIG. 7 is a diagram illustrating an apparatus configuration of anMME/AMF.

FIG. 8 is a diagram illustrating an apparatus configuration of anSMF/PGW/UPF.

FIG. 9 is a diagram illustrating an initial procedure.

FIG. 10 is a diagram illustrating a registration procedure.

FIG. 11 is a diagram illustrating a PDU session establishment procedure.

FIG. 12 is a diagram illustrating a network-initiated session managementprocedure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the best mode for carrying out the present invention willbe described with reference to the accompanying drawings. In the presentembodiment, one embodiment of a mobile communication system to which thepresent invention is applied will be described as an example.

1. System Overview

An outline of a mobile communication system according to the presentembodiment will be described with reference to FIG. 1, FIG. 2, FIG. 3and FIG. 4. FIG. 2 is a diagram illustrating details of an accessnetwork in the mobile communication system shown in FIG. 1. FIG. 3 is adiagram mainly illustrating details of a core network_A90 in the mobilecommunication system shown in FIG. 1. FIG. 4 is a diagram mainlyillustrating details of a core network_B190 in the mobile communicationsystem shown in FIG. 1. As shown in FIG. 1, the mobile communicationsystem 1 according to the present embodiment includes a terminalapparatus (also referred to as a user equipment or a mobile terminalapparatus) UE_A10, an access network (AN)_A, an access network_B, a corenetwork (CN)_A90, a core network_B190, a packet data network (PDN)_A6,and a data network (DN)_A5. It should be noted that a combination of theaccess network_A and the core network_A90 may be referred to as an EPS(Evolved Packet System; 4G mobile communication system), and acombination of the access network_B, the core network_B190, and theUE_A10 may be referred to as a 5GS (5G System; 5G mobile communicationsystem). The configurations of the 5GS and the EPS may not be limited tothese. For simplicity, the core network_A90, the core network_B, or acombination thereof may be referred to as a core network; the accessnetwork_A, the access network_B, or a combination thereof may bereferred to as an access network or a radio access network; and theDN_A5, the PDN_A6, or a combination thereof may be referred to as a DN.

Here, the UE_A10 may be an apparatus capable of connecting to a networkservice via a 3GPP access (also referred to as a 3GPP access network)and/or a non-3GPP access (also referred to as a non-3GPP accessnetwork). The UE may also be provided with a UICC (Universal IntegratedCircuit Card) or an eUICC (Embedded UICC). The UE_A10 may be a terminalapparatus capable of performing a wireless connection, and may be an ME(Mobile Equipment), an MS (Mobile Station), a CIoT (Cellular Internet ofThings) terminal (CIoT UE), or the like.

Besides, the UE_A10 can connect to an access network and/or a corenetwork. In addition, the UE_A10 can connect to the DN_A and/or thePDN_A via the access network and/or the core network. The UE_A10transmits and/or receives (communicates) user data to and/or from (with)the DNA and/or the PDN_A by using a PDU (Protocol Data Unit or PacketData Unit) session and/or a PDN (Packet Data Network) connection (alsoreferred to as a PDN connection). Furthermore, the communication of theuser data is not limited to IP (Internet Protocol) communication (IPv4or IPv6), and may be, for example, non-IP communication in the EPS, orEthernet communication (registered trademark) or Unstructuredcommunication in the 5GS.

Here, the IP communication refers to data communication using an IP, andis data communication implemented by transmitting and/or receiving an IPpacket with an IP header given. A payload portion included in the IPpacket may include user data transmitted and/or received by the UE_A10.In addition, the non-IP communication refers to data communicationwithout using an IP, and is data communication implemented bytransmitting and/or receiving data with no IP header given. For example,the non-IP communication may also be data communication implemented bytransmitting and/or receiving application data with no IP address given,or may be transmission and/or reception of user data transmitted and/orreceived by the UE_A10 with another header such as a MAC header, anEthernet (registered trademark) frame header, or the like given.

In addition, the PDU session refers to connectivity established betweenthe UE_A10 and the DN_A5 to provide a PDU connection service. Morespecifically, the PDU session may also be connectivity establishedbetween the UE_A10 and an external gateway. Here, the external gatewaymay be a UPF, a PGW (Packet Data Network Gateway), or the like. Inaddition, the PDU session may be a communication path established fortransmitting and receiving user data between UE_A10 and the core networkand/or the DN, or may be a communication path for transmitting andreceiving a PDU. Further, the PDU session may be a session establishedbetween the UE_A10 and the core network and/or the DN, or may be alogical communication path including a transmission path of one or morebearers and the like between apparatuses in the mobile communicationsystem 1. More specifically, a PDU session may be a connectionestablished by the UE_A10 with respect to the core network_B190 and/oran external gateway, or may be a connection established between theUE_A10 and a UPF. In addition, a PDU session may be connectivity and/ora connection between the UE_A10 and a UPF_A235 via an NR node_A122.Furthermore, a PDU session may be identified by a PDU session ID and/oran EPS bearer ID.

Moreover, the UE_A10 can transmit and/or receive the user data to and/orfrom an apparatus, such as an application server deployed in the DN_A5,by using a PDU session. In other words, the PDU session can transfer theuser data transmitted and/or received between the UE_A10 and anapparatus such as an application server deployed in the DN_A5.Furthermore, each apparatus (the UE_A10, an apparatus in the accessnetwork, and/or an apparatus in the core network, and/or an apparatus ina data network) may manage one or more pieces of identificationinformation associated with a PDU session. It should be noted that thesepieces of identification information may include at least one of an APN(Access Point Name), a TFT (Traffic Flow Template), a session type,application identification information, DN_A5 identificationinformation, NSI (Network Slice Instance) identification information,DCN (Dedicated Core Network) identification information, and accessnetwork identification information, and may further include otherinformation. Furthermore, in a case that a plurality of PDU sessions areestablished, the respective pieces of identification informationassociated with the PDU sessions may have the same content or differentcontents. Further, the NSI identification information is information foridentifying an NSI, and hereinafter may be an NSI ID or a Slice InstanceID.

In addition, as illustrated in FIG. 2, the access network_A and/or theaccess network B may be any of a UTRAN (Universal Terrestrial RadioAccess Network)_A20, an E-UTRAN (Evolved Universal Terrestrial RadioAccess Network)_A80, and an NG-RAN (5G-RAN)_A120. Hereinafter, theUTRAN_A20 and/or the E-UTRAN_A80 and/or the NG-RAN_A120 may be referredto as 3GPP access or a 3GPP access network, and a wireless LAN accessnetwork or a non-3GPP AN may be referred to as a non-3GPP access or anon-3GPP access network. Each radio access network includes an apparatusto which the UE_A10 is actually connected (e.g., a base stationapparatus or an access point), and the like.

For example, the E-UTRAN_A80 is an LTE access network and is configuredto include one or more eNBs_A45. The eNB_A45 is a radio base station towhich the UE_A10 is connected through an E-UTRA (Evolved Universalterrestrial Radio Access). In addition, in a case that a plurality ofeNBs are present in the E-UTRAN_A80, the eNBs may be connected to eachother.

In addition, the NG-RAN_A120 is a 5G access network, or may be the (R)ANillustrated in FIG. 4, and is configured to include one or more NR nodes(New Radio Access Technology nodes)_A122 and/or an ng-eNB. Furthermore,the NR node_A122 is a radio base station to which the UE_A10 isconnected through a 5G radio access and may also be referred to as gNB.Moreover, the ng-eNB may be an eNB (E-UTRA) constituting the 5G accessnetwork, may be connected to the core network_B190 via the NR node_A, ormay be directly connected to the core network_B190. In addition, in acase that there are a plurality of NR nodes_A122 and/or ng-eNBs in theNG-RAN_A120, the NR nodes_A122 and/or ng-eNBs may be connected to eachother.

Further, the NG-RAN_A120 may be an access network configured by theE-UTRA and/or the 5G Radio Access. In other words, the NG-RAN_A120 mayinclude an eNB_A45, or an NR node_A122, or both. In this case, theeNB_A45 and the NR node_A122 may be similar apparatuses. Therefore, theNR node_A122 can be substituted with the eNB_A45.

The UTRAN_A20 is an access network of a 3G mobile communication system,and is configured to include an RNC (Radio Network Controller)_A24 andan NB (Node B)_A22. The NB_A22 is a radio base station to which theUE_A10 is connected through a UTRA (Universal Terrestrial Radio Access),and the UTRAN_A20 may include one or more radio base stations.Furthermore, an RNC_A24 is a controller for connecting the corenetwork_A90 to the NB_A22, and the UTRAN_A20 may be configured toinclude one or more RNCs. In addition, the RNC_A24 may be connected toone or more NBs_A22.

It should be noted that, in the present specification, the expressionthat the UE_A10 is connected to each radio access network means that theUE_A10 is connected to a base station apparatus, an access point, or thelike included in each radio access network, and that data, signals, andthe like are also transmitted and/or received via the base stationapparatus and the access point. In addition, control messagestransmitted and/or received between the UE_A10 and the core network_B190may be the same control message regardless of the type of accessnetwork. Therefore, the expression that the UE_A10 and the corenetwork_B190 transmit and/or receive a message to and/or from each othervia the NR node_A122 may be equivalent to the expression that the UE_A10and the core network_B190 transmit a message to each other via theeNB_A45.

Further, the access network is a radio network connected to the UE_A10and/or the core network. The access network may be a 3GPP access networkor a non-3GPP access network. Furthermore, the 3GPP access network maybe the UTRAN_A20, the E-UTRAN_A80, and the NG-RAN (Radio AccessNetwork)_A120, and the non-3GPP access network may be a wireless LANaccess point (WLAN AN). In addition, the UE_A10 may be connected to theaccess network in order to connect to the core network, or may beconnected to the core network via the access network.

In addition, the DN_A5 and the PDN_A6 are data networks that providecommunication services to the UE_A10, may be configured as packet dataservice networks, or may be configured for each service. Also, the DN_A5may include a connected communication terminal. Therefore, theconnection to the DN_A5 may refer to the connection to a communicationterminal or a server apparatus deployed in the DN_A5. Furthermore,transmission and/or reception of user data to and/or from the DN_A5 mayrefer to transmission and/or reception of user data to and/or from acommunication terminal or a server apparatus deployed in the DN_A5. Inaddition, although the DN_A5 is outside the core network in FIG. 1, itmay be located within the core network.

In addition, the core network_A90 and/or the core network_B190 may beconfigured as an apparatus within one or more core networks. Here, anapparatus within the core network may be an apparatus that performs partor all of processing or functions of apparatuses included in the corenetwork_A90 and/or the core network_B190. It should be noted that theapparatus within the core network may be referred to as a core networkapparatus.

Furthermore, the core network is an IP mobile communication networkoperated by a mobile network operator (MNO) and connected to an accessnetwork and/or a DN. The core network may be a core network for a mobilecommunication operator to operate and manage the mobile communicationsystem 1, or may be a core network for a virtual mobile communicationoperator or a virtual mobile communication service provider such as anMVNO (Mobile Virtual Network Operator) or an MVNE (Mobile VirtualNetwork Enabler). The core network_A90 may be an EPC (Evolved PacketCore) constituting an EPS (Evolved Packet System), and the corenetwork_B190 may be a 5GC (5G core network) constituting a 5GS. Further,the core network_B190 may be a core network for a system that provides5G communication services. Conversely, the EPC may be the corenetwork_A90, and the 5GC may be the core network_B190. It should benoted that the core network_A90 and/or the core network_B190 may not belimited to the above, and may be a network for providing mobilecommunication services.

Next, the core network_A90 will be described. The core network_A90 mayinclude at least one of an HSS (Home Subscriber Server)_A 50, an AAA(Authentication Authorization Accounting), a PCRF (Policy and ChargingRules Function), a PGW_A30, an ePDG, an SGW_A35, an MME (MobilityManagement Entity)_A40, an SGSN (Serving GPRS Support Node), and anSCEF. In addition, these may be configured as NFs (Network Functions).The NF may be a processing function included in a network. In addition,the core network_A90 can be connected to a plurality of radio accessnetworks (e.g., the UTRAN_A20 and the E-UTRAN_A80).

Although only the HSS (HSS_A50), the PGW (PGW_A30), the SGW (SGW_A35),and the MME (MME_A40) among the network functions are described in FIG.3 for simplicity, it does not mean that no other apparatuses and/or NFsare included therein. For simplicity, the UE_A10 is also referred to asa UE, the HSS_A50 is also referred to as an HSS, the PGW_A30 is alsoreferred to as a PGW, the SGW_A35 is also referred to as an SGW, theMME_A40 is also referred to as an MME, and the DN_A5 and/or the PDN_A6is also referred to as a DN or a PDN.

Each apparatus included in the core network_A90 will be brieflydescribed below.

The PGW_A30 is a relay apparatus that is connected to the DN, theSGW_A35, the ePDG, the WLAN ANa70, the PCRF, and the AAA, and transfersuser data as a gateway between the DN (the DN_A5 and/or the PDN_A6) andthe core network_A90. In addition, the PGW_A30 may serve as a gatewayfor IP communication and/or non-IP communication. Furthermore, thePGW_A30 may have a function of transferring the IP communication, or mayhave a function of performing conversion between the non-IPcommunication and the IP communication. Moreover, a plurality of suchgateways may be deployed in the core network_A90. Also, the plurality ofgateways deployed may serve as gateways for connecting the corenetwork_A90 to a single DN.

It should be noted that a user plane (U-Plane; UP) may be acommunication path for transmitting and/or receiving user data, and mayinclude a plurality of bearers. Further, a control plane (C-Plane; CP)may be a communication path for transmitting and/or receiving a controlmessage, and may include a plurality of bearers.

Furthermore, the PGW_A30 may be connected to the SGW, the DN, a UPF(User Plane Function) and/or a SMF (Session Management Function), andmay be connected to the UE_A10 via the U-Plane. Moreover, the PGW_A30may be configured integrally with the UPF_A235 and/or the SMF_A230.

The SGW_A35 is a relay apparatus that is connected to the PGW_A30, theMME_A40, the E-UTRAN_A80, the SGSN, and the UTRAN_A20, and transfersuser data as a gateway between the core network_A90 and the 3GPP accessnetwork (the UTRAN_A20, a GERAN, or the E-UTRAN_A80).

The MME_A40 is a control apparatus that is connected to the SGW_A35, theaccess network, the HSS_A50, and the SCEF and performs locationinformation management, including mobility management of the UE_A10 viathe access network, and access control. Further, the MME_A40 may includea function as a session management apparatus that manages a sessionestablished by the UE_A10. In addition, a plurality of such controlapparatuses may be deployed in the core network_A90, and, for example, alocation management apparatus different from the MME_A40 may also beconfigured. Similar to the MME_A40, a location management apparatusdifferent from the MME_A40 may be connected to the SGW_A35, the accessnetwork, the SCEF, and the HSS_A50. Furthermore, the MME_A40 may beconnected to an AMF (Access and Mobility Management).

In addition, when a plurality of MMEs are included in the corenetwork_A90, the MMEs may be connected to each other. As a result, acontext of the UE_A10 may be transmitted and/or received between theMMEs. In this way, the MME_A40 is a management apparatus that transmitsand/or receives control information related to mobility management andsession management to and/or from the UE_A10. In other words, theMME_A40 may be a control apparatus for a control plane (C-Plane; CP).

Further, although the example in which the MME_A40 is configured to beincluded in the core network_A90 has been described, the MME_A40 may bea management apparatus configured in one or more core networks, DCNs, orNSIs, or may be a management apparatus connected to one or more corenetworks, DCNs, or NSIs. Here, a plurality of DCNs or NSIs may beoperated by a single network operator or by different network operatorsrespectively.

In addition, the MME_A40 may be a relay apparatus that transfers userdata as a gateway between the core network_A90 and the access network.Besides, the user data transmitted and/or received by the MME_A40serving as a gateway may be small data.

Further, the MME_A40 may be an NF that functions for mobility managementof the UE_A10 or the like, or an NF that manages one or more NSIs. Inaddition, the MME_A40 may be an NF that functions for one or more of theabove functions. Besides, the NF may be one or more apparatuses deployedin the core network_A90, may be a CP function (hereinafter, alsoreferred to as a Control Plane Function (CPF) or a Control Plane NetworkFunction) for control information and/or control messages, or may be acommon CP function shared between a plurality of network slices.

Here, the NF refers to a processing function configured in a network. Inother words, the NF may be a function apparatus such as an MME, an SGW,a PGW, a CPF, an AMF, an SMF, or a UPF, or may be a function such as MM(Mobility Management) or SM (Session Management), or capabilityinformation. In addition, the NF may be a function apparatus forimplementing a single function, or may be a function apparatus forimplementing a plurality of functions. For example, an NF forimplementing the MM function and an NF for implementing the SM functionmay be separately present, or an NF for implementing both the MMfunction and the SM function may be present.

The HSS_A50 is a management node that is connected to the MME_A40, theAAA, and the SCEF, and manages subscriber information. The subscriberinformation of the HSS_A50 is referred to, for example, at the time ofaccess control of the MME_A40. Further, the HSS_A50 may be connected toa location management apparatus different from the MME_A40. For example,the HSS_A50 may be connected to CPF_A140.

Furthermore, the HSS_A50 and UDM (Unified Data Management)_A245 may beconfigured as different apparatuses and/or NFs, or may be configured asthe same apparatus and/or NF.

The AAA is connected to the PGW30, the HSS_A50, the PCRF, and the WLANANa70, and performs access control with respect to the UE_A10 connectedvia the WLAN ANa70.

The PCRF is connected to the PGW_A30, the WLAN ANa75, the AAA, the DN_A5and/or the PDN_A6, and performs QoS management for data delivery. Forexample, the PCRF performs QoS management for a communication pathbetween the UE_A10 and the DN_A5, and/or the PDN_A6. Further, the PCRFmay be an apparatus that generates and/or manages a PCC (Policy andCharging Control) rule and/or a routing rule used by each apparatus totransmit and/or receive user data.

In addition, the PCRF may be a PCF that generates and/or manages apolicy. More specifically, the PCRF may be connected to the UPF_A235.

The ePDG is connected to the PGW30 and the WLAN ANb75 and delivers userdata as a gateway between the core network_A90 and the WLAN ANb75.

The SGSN is a control apparatus that is connected to the UTRAN_A20, theGERAN, and the SGW_A35 and performs location management between a 3G/2Gaccess network (UTRAN/GERAN) and an LTE (4G) access network (E-UTRAN).In addition, the SGSN has functions of selecting the PGW and the SGW,managing a time zone of the UE_A10, and selecting the MME_A40 at thetime of a handover to the E-UTRAN.

The SCEF is a relay apparatus that is connected to the DN_A5 and/or thePDN_A6, the MME_A40, and the HSS_A50 and transfers the user data as agateway connecting the DN_A5 and/or the PDN_A6 to the core network_A90.Besides, the SCEF may serve as a gateway for non-IP communication.Further, the SCEF may include a function of performing conversionbetween non-IP communication and IP communication. In addition, aplurality of such gateways may be deployed in the core network_A90.Furthermore, a plurality of gateways connecting the core network_A90 toa single DN_A5 and/or PDN_A6 and/or DN may also be deployed. Besides,the SCEF may be configured outside or inside the core network.

Next, the core network_B190 will be described. The core network_B190 mayinclude at least one of an AUSF (Authentication Server Function), an AMF(Access and Mobility Management Function)_A240, a UDSF (UnstructuredData Storage Network Function), an NEF (Network Exposure Function), anNRF (Network Repository Function), a PCF (Policy Control Function), anSMF (Session Management Function)_A230, a UDM (Unified Data Management),a UPF (User Plane Function)_A235, an AF (Application Function), and anN3IWF (Non-3GPP InterWorking Function). In addition, these may beconfigured as NFs (Network Functions). The NF may refer to a processingfunction configured in a network.

For simplicity, FIG. 4 only shows an AMF (AMF_A240), an SMF (SMF_A230),and a UPF (UPF_A235) among the above elements, but it does not mean thatelements (apparatuses and/or NFs (Network Functions)) other than theabove are not included therein. It should be noted that, for simplicity,the UE_A10 is also referred to as a UE, the AMF_A240 is also referred toas an AMF, the SMF_A230 is also referred to as an SMF, the UPF_A235 isalso referred to as a UPF, and the DN_A5 is also referred to as a DN.

In addition, FIG. 4 shows an N1 interface (hereinafter, also referred toas a reference point), an N2 interface, an N3 interface, an N4interface, an N6 interface, an N9 interface, and an N11 interface. Here,the N1 interface is an interface between the UE and the AMF, the N2interface is an interface between the (R)AN (access network) and theAMF, and the N3 interface is an interface between the (R)AN (accessnetwork) and the UPF, the N4 interface is an interface between the SMFand the UPF, the N6 interface is an interface between the UPF and theDN, the N9 interface is an interface between the UPF and the UPF, andthe N11 interface is an interface between the AMF and the SMF. Theseinterfaces can be used to perform communication between the apparatuses.Here, the (R)AN will also be referred to as an NG RAN.

Each apparatus included in the core network_B190 will be brieflydescribed below.

First, the AMF_A240 is connected to another AMF, the SMF (SMF_A230), theaccess network (i.e., the UTRAN_A20, the E-UTRAN_A80, or anNG-RAN_A120), a UDM, an AUSF, and a PCF. The AMF_A240 may function forregistration management, connection management, reachability management,mobility management of the UE_A10 or the like, transmission of a sessionmanagement (SM) message between the UE and the SMF, accessauthentication (or access authorization), a security anchor function(SEA), security context management (SCM), support for the N2 interfacefor the N3IWF, support for transmission and/or reception of NAS signalsto and/or from the UE via the N3IWF, authentication of the UE connectedvia the N3IWF, management of registration management (RM) states,management of connection management (CM) states, and the like. Inaddition, one or more AMFs_A240 may be deployed within the corenetwork_B190. In addition, the AMF_A240 may be an NF that manages one ormore NSIs (Network Slice Instances). In addition, the AMF_A240 may alsobe a common control plane network function (CCNF; Common CPNF) shared bya plurality of NSIs.

In addition, the RM state includes a deregistered state (RM-DEREGISTEREDstate) and a registered state (RM-REGISTERED state). In theRM-DEREGISTERED state, the UE is not registered in the network, so thatthe UE context in the AMF does not have valid location information orrouting information for the UE, so the AMF is unable to reach the UE. Inthe RM-REGISTERED state, the UE is registered with the network, so thatthe UE can receive services that require registration with the network.

In addition, the CM state includes a non-connected state (CM-IDLE state)and a connected state (CM-CONNECTED state). In the CM-IDLE state, the UEstays in the RM-REGISTERED state, but does not have a NAS signalingconnection established with the AMF via the N1 interface. In addition,in the CM-IDLE state, the UE does not have an N2 interface connection(N2 connection) or an N3 interface connection (N3 connection). On theother hand, in the CM-CONNECTED state, the UE has an NAS signalingconnection established with the AMF via the N1 interface. In addition,in the CM-CONNECTED state, the UE may have an N2 interface connection(N2 connection) and/or an N3 interface connection (N3 connection).

In addition, the SMF_A230 may have following functions: a sessionmanagement (SM) function for PDU sessions or the like, an IP addressallocation for UE and management function, a UPF selection and controlfunction, a UPF configuration function for routing traffic to anappropriate destination, a function for reporting arrival of downlinkdata (Downlink Data Notification), a function for providing SMinformation unique to an AN (each AN) to be transmitted to the AN overthe N2 interface via the AMF, a function for determining an SSC mode(Session and Service Continuity mode) for a session, a roaming function,and the like. In addition, the SMF_A230 may be connected to theAMF_A240, the UPF_A235, the UDM, and the PCF.

In addition, the UPF_A235 is connected to the DN_A5, the SMF_A230,another UPF, and the access network (i.e., the UTRAN_A20, theE-UTRAN_A80, or the NG-RAN_A120). The UPF_A235 may have the followingfunctions: an anchor for intra-RAT mobility or inter-RAT mobility,packet routing & forwarding, a UL CL (Uplink Classifier) function forsupporting routing of a plurality of traffic flows for one DN, abranching point function for supporting a multi-homed PDU session, QoSprocessing for a user plane, verification of uplink traffic, bufferingof downlink packets, a function for triggering downlink datanotification, and the like. In addition, the UPF_A235 may be a relayapparatus that transfers the user data as a gateway between the DN_A5and the core network_B190. Further, the UPF_A235 may serve as a gatewayfor IP communication and/or non-IP communication. Furthermore, theUPF_A235 may have a function of transferring the IP communication, ormay have a function of performing conversion between the non-IPcommunication and the IP communication. Moreover, a plurality ofdeployed gateways may serve as gateways for connecting the corenetwork_B190 to a single DN. Besides, the UPF_A235 may have connectivitywith other NFs, or may be connected to each apparatus via other NFs.

It should be noted that a UPF_C239 (also referred to as a branchingpoint or an uplink classifier), which is a UPF different from theUPF_A235, may be present as an apparatus or an NF between the UPF_A235and the access network. When the UPF_C239 is present, a PDU sessionbetween the UE_A10 and the DN_A5 is established via the access network,the UPF_C239, and the UPF_A235.

In addition, the AUSF is connected to the UDM and the AMF_A240. The AUSFfunctions as an authentication server.

The UDSF provides a function for all NFs to store or retrieveinformation as unstructured data.

The NEF provides means for safely providing services and capabilitiesprovided through the 3GPP network. Information received from another NFis stored as structured data.

When the NRF receive an NF Discovery Request from an NF instance, theNRF provides the NF with information of discovered NF instances or holdsinformation of available NF instances or services supported by theinstances.

The PCF is connected to the SMF (SMF_A230), the AF, and the AMF_A240.The PCF provides a policy rule and the like.

The UDM is connected to the AMF_A240, the SMF (SMF_A230), the AUSF, andthe PCF. The UDM includes a UDM FE (application front end) and a UDR(User Data Repository).

The UDM FE performs processing of authentication information(credentials), location management, subscriber management (subscriptionmanagement), and the like. The UDR stores data required to be providedby the UDM FE and policy profiles required by the PCF.

The AF is connected to the PCF. The AF affects traffic routing or isinvolved in policy control.

The N3IWF provides the functions of establishing an IPsec tunnel withthe UE, relaying NAS (N1) signaling between the UE and the AMF,processing N2 signaling transmitted from the SMF and relayed by the AMF,establishing IPsec Security Association (IPsec SA), relaying a userplane packet between the UE and the UPF, selecting the AMF, and thelike.

In addition, an S1 mode is a UE mode in which messages can betransmitted and received by using an S1 interface. Further, the S1interface may include an S1-MME interface, an S1-U interface and an X2interface that connects radio base stations.

The UE in the S1 mode can perform, for example, an access to the EPC viaan eNB that provides an E-UTRA function or to the EPC via an en-gNB thatprovides an NR function.

Although the access to the EPC via the eNB that provides the E-UTRAfunction and the access to the EPC via the en-gNB that provides the NRfunction are set to the S1 mode, they may be set to different modes,respectively.

In addition, an N1 mode is a UE mode in which the UE can access a 5GCvia a 5G access network. In addition, an N1 mode may also be a UE modein which messages can be transmitted and received by using an N1interface. Further, the N1 interface may include an N1 interface and anXn interface that connects radio base stations.

The UE in the N1 mode can perform, for example, an access to a 5GC viaan ng-eNB that provides an E-UTRA function or to a 5GC via a gNB thatprovides an NR function.

Furthermore, the access to the 5GC via the ng-eNB that provides theE-UTRA function and the access to the 5GC via the gNB that provides theNR function are set to the N1 mode, but they may be set to differentmodes, respectively.

[1.2. Configuration of Each Apparatus]

Hereinafter, a configuration of each apparatus will be described. Itshould be noted that some or all functions of each apparatus and eachunit of an apparatus described below may operate on physical hardware ormay operate on logical hardware that is virtually configured on ageneral-purpose hardware.

[1.2.1. Configuration of UE]

First, an example of an apparatus configuration of the UE_A10 isillustrated in FIG. 5. As illustrated in FIG. 5, the UE_A10 includes acontrol unit_A500, a transmission and/or reception unit_A520, and astorage unit_A540. The transmission and/or reception unit_A520 and thestorage unit_A540 are connected to the control unit_A500 via a bus. Inaddition, an external antenna 410 is connected to the transmissionand/or reception unit_A520.

The control unit_A500 is a functional unit for controlling the entireUE_A10, and implements various processing of the entire UE_A10 byreading out and executing various types of information and programsstored in the storage unit_A540.

The transmission and/or reception unit_A520 is a functional unit for theUE_A10 to connect to the base station (the UTRAN_A20, the E-UTRAN_A80,or the NG-RAN_A120) and/or the wireless LAN access point (WLAN AN) inthe access network, and to connect to the access network. In otherwords, the UE_A10 can connect to the base station and/or the accesspoint in the access network via the external antenna 410 connected tothe transmission and/or reception unit_A520. Specifically, the UE_A10can transmit and/or receive user data and/or control information toand/or from the base station and/or the access point in the accessnetwork via the external antenna 410 connected to the transmissionand/or reception unit_A520.

The storage unit_A540 is a functional unit that stores programs, data,and the like required for each operation of the UE_A10, and includes,for example, a semiconductor memory, an HDD (Hard Disk Drive), an SSD(Solid State Drive), and the like. The storage unit_A540 storesidentification information, control information, a flag, a parameter, arule, a policy, and the like included in a control message which istransmitted and/or received in a communication procedure describedbelow.

[1.2.2. eNB/NR Node]

Next, FIG. 6 illustrates an example of an apparatus configuration of theeNB_A45 and the NR node_A122. As illustrated in FIG. 6, the eNB_A45 andthe NR node_A122 include a control unit_B600, a network connectionunit_B620, a transmission and/or reception unit_B630, and a storageunit_B640. The network connection unit_B620, the transmission and/orreception unit_B630, and the storage unit_B640 are connected to thecontrol unit_B600 via a bus. In addition, an external antenna 510 isconnected to the transmission and/or reception unit_B630.

The control unit_B600 is a functional unit for controlling the entireeNB_A45 and NR node_A122, and implements various processing of theentire eNB_A45 and NR node_A122 by reading out and executing varioustypes of information and programs stored in the storage unit_B640.

The network connection unit_B620 is a functional unit for the eNB_A45and the NR node_A122 to connect to the AMF_A240 and the UPF_A235 withinthe core network. In other words, the eNB_A45 and the NR node_A122 canbe connected to the AMF_A240 and the UPF_A235 within the core networkvia the network connection unit_B620. Specifically, the eNB_A45 and theNR node_A122 can transmit and/or receive user data and/or controlinformation to and/or from the AMF_A240 and/or the UPF_A235 via thenetwork connection unit_B620.

The transmission and/or reception unit_B630 is a functional unit for theeNB_A45 and the NR node_A122 to connect to the UE_A10. In other words,the eNB_A45 and the NR node_A122 can transmit and/or receive user dataand/or control information to and/or from the UE_A10 via thetransmission and/or reception unit_B630.

The storage unit_B640 is a functional unit for storing programs, data,and the like required for each operation of the eNB_A45 and the NRnode_A122. The storage unit_B640 includes, for example, a semiconductormemory, an HDD, an SSD, and the like. The storage unit_B640 storesidentification information, control information, a flag, a parameter,and the like included in a control message which is transmitted and/orreceived in a communication procedure described below. The storageunit_B640 can store the information as context for each UE_A10.

[1.2.3. Configuration of MME/AMF]

Next, FIG. 7 illustrates an example of an apparatus configuration of theMME_A40 and/or the AMF_A240. As illustrated in FIG. 7, the MME_A40and/or the AMF_A240 include a control unit_C700, a network connectionunit_C720, and a storage unit_C740. The network connection unit_C720 andthe storage unit_C740 are connected to the control unit_C700 via a bus.In addition, the storage unit_C740 stores a context 642.

The control unit_C700 is a functional unit for controlling the entireMME_A40 or AMF_A240, and implements various processing of the entireAMF_A240 by reading out and executing various types of information andprograms stored in the storage unit_C740.

The network connection unit_C720 is a functional unit for the MME_A40and/or the AMF_A240 to connect to another MME_A40, AMF 240, SMF_A230, abase station (the UTRAN_A20, the E-UTRAN_A80 or the NG-RAN_A120) withinthe access network and/or a wireless LAN access point (WLAN AN), theUDM, the AUSF, and the PCF. In other words, the MME_A40 or the AMF_A240can transmit and/or receive via the network connection unit_C720 userdata and/or control information to and/or from the base station and/oran access point within the access network, the UDM, the AUSF, and thePCF.

The storage unit_C740 is a functional unit for storing programs, data,and the like required for each operation of the MME_A40 or the AMF_A240.The storage unit_C740 includes, for example, a semiconductor memory, anHDD, an SSD, and the like. The storage unit_C740 stores identificationinformation, control information, a flag, a parameter, and the likeincluded in a control message which is transmitted and/or received in acommunication procedure described below. The context 642 stored in thestorage unit_C740 may include a context stored for each UE, a contextstored for each PDU session, and a context stored for each bearer. Thecontext stored for each UE may include an IMSI, an MSISDN, an MM State,a GUTI, a ME Identity, a UE radio access capability, a UE networkcapability, an MS network capability, an access restriction, an MMEF-TEID, an SGW F-TEID, an eNB address, an MME UE S1AP ID, an eNB UE S1APID, an NR node address, an NR node ID, a WAG address, and a WAG ID. Inaddition, the context stored for each PDU session may include an APN inUse, an Assigned Session Type, IP address(es), a PGW F-TEID, an SCEF ID,and a Default Bearer. In addition, the context stored for each bearermay include an EPS Bearer ID, a TI, a TFT, an SGW F-TEID, a PGW F-TEID,an MME F-TEID, an eNB address, an NR node address, a WAG address, an eNBID, an NR node ID, and a WAG ID.

[1.2.4. Configuration of SMF]

Next, FIG. 8 illustrates an example of an apparatus configuration of theSMF_A230. As illustrated in FIG. 8, the SMF_A230 includes a controlunit_D800, a network connection unit_D820, and a storage unit_D840. Thenetwork connection unit_D820 and the storage unit_D840 are connected tothe control unit_D800 via a bus. In addition, the storage unit_D840stores a context 742.

The control unit_D800 of the SMF_A230 is a functional unit forcontrolling the entire SMF_A230, and implements various processing ofthe entire SMF_A230 by reading out and executing various types ofinformation and programs stored in the storage unit_D840.

In addition, the network connection unit_D820 of the SMF_A230 is afunctional unit for the SMF_A230 to connect to the AMF_A240, theUPF_A235, the UDM, and the PCF. In other words, the SMF_A230 cantransmit and/or receive via the network connection unit_D820 user dataand/or control information to and/or from the AMF_A240, the UPF_A235,the UDM, and the PCF.

In addition, the storage unit_D840 of the SMF_A230 is a functional unitfor storing programs, data, and the like required for each operation ofthe SMF_A230. The storage unit_D840 of the SMF_A230 includes, forexample, a semiconductor memory, an HDD, an SSD, or the like. Thestorage unit_D840 of the SMF_A230 stores identification information,control information, a flag, a parameter, and the like included in acontrol message which is transmitted and/or received in thecommunication procedure described below. In addition, the context 742stored in the storage unit_D840 of the SMF_A230 may include a contextstored for each UE, a context stored for each APN, a context stored foreach PDU session, and a context stored for each bearer. The contextstored for each UE may include an IMSI, an ME Identity, an MSISDN, and aRAT type. The context stored for each APN may include an APN in Use. Itshould be noted that the context stored for each APN may be stored foreach Data Network Identifier. The context stored for each PDU sessionmay include an Assigned Session Type, IP address(es), an SGW F-TEID, aPGW F-TEID, and a Default Bearer. The context stored for each bearer mayinclude an EPS Bearer ID, a TFT, an SGW F-TEID, and a PGW F-TEID.

[1.2.5. Configuration of PGW/UPF]

Next, FIG. 8 illustrates an example of an apparatus configuration of thePGW_A30 and/or the UPF_A235. As illustrated in FIG. 8, each of thePGW_A30 and/or the UPF_A235 includes a control unit_D800, a networkconnection unit_D820, and a storage unit_D840. The network connectionunit_D820 and the storage unit_D840 are connected to the controlunit_D800 via a bus. In addition, the storage unit_D840 stores a context742.

The control unit_D800 of the PGW_A30 or the UPF_A235 is a functionalunit for controlling the entire PGW_A30 or UPF_A235, and implementsvarious processing of the entire PGW_A30 or the UPF_A235 by reading outand executing various types of information and programs stored in thestorage unit_D840.

In addition, the network connection unit_D820 of the PGW_A30 or theUPF_A235 is a functional unit for the PGW_A30 or the UPF_A235 to connectto the DN (that is, the DN_A5), the SMF_A230, another UPF_A235, and theaccess network (i.e., the UTRAN_A20, the E-UTRAN_A80, and theNG-RAN_A120). In other words, the UPF_A235 can transmit and/or receivevia the network connection unit_D820 user data and/or controlinformation to and from the DN (i.e., the DN_A5), the SMF_A230, anotherUPF_A235, and the access network (i.e., the UTRAN_A20, the E-UTRAN_A80,or the NG-RAN_A120).

In addition, the storage unit_D840 of the UPF_A235 is a functional unitfor storing programs, data, and the like required for each operation bythe UPF_A235. The storage unit_D840 of the UPF_A235 includes, forexample, a semiconductor memory, an HDD, an SSD, or the like. Thestorage unit_D840 of the UPF_A235 stores identification information,control information, a flag, a parameter, and the like included in acontrol message which is transmitted and/or received in thecommunication procedure described below. In addition, the context 742stored in the storage unit_D840 of the UPF_A235 may include a contextstored for each UE, a context stored for each APN, a context stored foreach PDU session, and a context stored for each bearer. The contextstored for each UE may include an IMSI, an ME Identity, an MSISDN, and aRAT type. The context stored for each APN may include an APN in Use. Itshould be noted that the context stored for each APN may be stored foreach Data Network Identifier. The context stored for each PDU sessionmay include an Assigned Session Type, IP address(es), an SGW F-TEID, aPGW F-TEID, and a Default Bearer. The context stored for each bearer mayinclude an EPS Bearer ID, a TFT, an SGW F-TEID, and a PGW F-TEID.

[1.2.6. Information Stored in Storage Unit of Each Above-DescribedApparatus]

Next, each piece of information stored in the storage unit of each ofthe above-described apparatuses will be described.

The IMSI (International Mobile Subscriber Identity) is permanentidentification information of a subscriber (user), and is identificationinformation assigned to a user using the UE. The IMSI stored by theUE_A10, the MME_A40/CPF_A140/AMF_A2400, and the SGW_A35 may be the sameas the IMSI stored by an HSS_A50.

The EMM state/MM state indicates a mobility management state of theUE_A10 or the MME_A40/CPF_A140/AMF_A240. For example, the EMM state/MMstate may be an EMM-REGISTERED state (registered state) in which theUE_A10 is registered in a network, and/or an EMM-DEREGISTERD state(non-registered state) in which the UE_A10 is not registered in anetwork. In addition, the EMM state/MM state may be an ECM-CONNECTEDstate in which a connection is maintained between the UE_A10 and thecore network, and/or an ECM-IDLE state in which the connection isreleased. It should be noted that the EMM state/MM state may beinformation for distinguishing a state in which the UE_A10 is registeredin an EPC from a state in which the UE_A10 is registered in an NGC or5GC.

The GUTI (Globally Unique Temporary Identity) is temporaryidentification information of the UE_A10. The GUTI includesidentification information (Globally Unique MME Identifier (GUMMEI)) ofthe MME_A40/CPF_A140/AMF_A240 and identification information(M-Temporary Mobile Subscriber Identity (M-TMSI)) of the UE_A10 in aspecific MME_A40/CPF_A140/AMF_A240. The ME identity is an ID of theUE_A10 or the ME, and may be, for example, an IMEI (International MobileEquipment Identity) or an IMEISV (IMEI Software Version). The MSISDNrepresents a basic telephone number of the UE_A10. The MSISDN stored bythe MME_A40/CPF_A140/AMF_A240 may be information indicated by thestorage unit of the HSS_A50. In addition, the GUTI may includeinformation for identifying the CPF_140.

The MME F-TEID is information for identifying theMME_A40/CPF_A140/AMF_A240. The MME F-TEID may include an IP address ofthe MME_A40/CPF_A140/AMF_A240, a TEID (Tunnel Endpoint Identifier) ofthe MME_A40/CPF_A140/AMF_A240, or both of them. In addition, the IPaddress of the MME_A40/CPF_A140/AMF_A240 and the TEID of theMME_A40/CPF_A140/AMF_A240 may be stored independently. In addition, theMME F-TEID may be identification information for user data, oridentification information for control information.

The SGW F-TEID is information for identifying the SGW_A35. The SGWF-TEID may include an IP address of the SGW_A35, a TEID of the SGW_A35,or both of them. In addition, the IP address of the SGW_A35 and the TEIDof the SGW_A35 may be stored independently. In addition, the SGW F-TEIDmay be identification information for user data, or identificationinformation for control information.

The PGW F-TEID is information for identifying thePGW_A30/UPGW_A130/SMF_A230/UPF_A235. The PGW F-TEID may include an IPaddress of the PGW_A30/UPGW_A130/SMF_A230/UPF_A235, a TEID of thePGW_A30/UPGW_A130/SMF_A230/UPF_A235, or both of them. In addition, theIP address of the PGW_A30/UPGW_A130/SMF_A230/UPF_A235 and the TEID ofthe PGW_A30/UPGW_A130/SMF_A230/UPF_A235 may be stored independently. Inaddition, the PGW F-TEID may be identification information for userdata, or identification information for control information.

The eNB F-TEID is information for identifying the eNB_A45. The eNBF-TEID may include an IP address of the eNB_A45, a TEID of the eNB_A45,or both of them. In addition, the IP address of the eNB_A45 and the TEIDof the SGW_A35 may be stored independently. In addition, the eNB F-TEIDmay be identification information for user data, or identificationinformation for control information.

In addition, the APN may be identification information for identifyingthe core network and an external network such as the DN. Further, theAPN can also be used as information for selecting a gateway such as thePGW_A30/UPGW_A130/UPF_A235 for connecting the core network A_90. Itshould be noted that the APN may be a DNN (Data Network Name).Therefore, the APN may be represented by a DNN, or the DNN may berepresented by the APN.

In addition, the APN may be identification information for identifyingsuch a gateway, or identification information for identifying anexternal network such as the DN. Further, when a plurality of gatewaysconnecting the core network and the DN are deployed, there may be aplurality of gateways that can be selected according to the APN.Furthermore, one gateway may be selected among such a plurality ofgateways in another method that uses identification information otherthan the APN.

The UE radio access capability is identification information indicatinga radio access capability of the UE_A10. The UE network capabilityincludes a security algorithm and a key derivation function supported bythe UE_A10. The MS network capability is information including, for theUE_A10 having GERAN_A25 and/or UTRAN_A20 function(s), one or more piecesof information required for an SGSN_A42. The access restriction isregistration information for access restriction. The eNB address is anIP address of the eNB_A45. The MME UE S1AP ID is information foridentifying the UE_A10 within the MME_A40/CPF_A140/AMF_A240. The eNB UES1AP ID is information for identifying the UE_A10 within the eNB_A45.

The APN in Use is an APN recently used. The APN in Use may be a datanetwork identifier. The APN may include identification information of anetwork and identification information of a default operator. Further,the APN in Use may be information for identifying a DN with which a PDUsession is established.

The Assigned Session Type is information indicating a PDU session type.The Assigned Session Type may be Assigned PDN Type. The PDU session typemay be IP or non-IP. Furthermore, when the PDU session type is IP,information indicating a PDN type allocated by the network may befurther included. It should be noted that the Assigned Session Type maybe IPv4, IPv6, or IPv4v6.

In addition, if it is not specifically specified, the IP address refersto an IP address allocated to the UE. The IP address may be an IPv4address, an IPv6 address, an IPv6 prefix, or an interface ID. It shouldbe noted that when the Assigned Session Type indicates non-IP, an IPaddress element may not be included.

A DN ID is identification information for identifying the corenetwork_B190 and an external network such as the DN. Further, the DN IDcan also be used as information for selecting a gateway such as theUPGW_A130 or the PF_A235 connecting the core network_B190.

In addition, the DN ID may be identification information for identifyingsuch a gateway, or identification information for identifying anexternal network such as the DN. Further, when a plurality of gatewaysconnecting the core network_B190 and the DN are deployed, there may be aplurality of gateways that can be selected according to the DN ID.Furthermore, one gateway may be selected among such a plurality ofgateways in another method that uses identification information otherthan the DN ID.

Moreover, the DN ID may be information equivalent to the APN ordifferent from the APN. If the DN ID is information different from theAPN, each apparatus may manage information indicating a correspondingrelationship between the DN ID and the APN, perform a procedure toinquire the APN by using the DN ID, or perform a procedure to inquirethe DN ID by using the APN.

The SCEF ID is an IP address of an SCEF_A46 used in a PDU session. TheDefault Bearer is information acquired and/or generated at the time whena PDU session is established and is EPS bearer identificationinformation for identifying a default bearer associated with the PDUsession.

The EPS Bearer ID is identification information of an EPS bearer. Inaddition, the EPS Bearer ID may be identification information foridentifying an SRB (Signalling Radio Bearer) and/or a CRB (Control-planeRadio bearer), or identification information for identifying a DRB (DataRadio Bearer). A TI (Transaction Identifier) is identificationinformation for identifying a bidirectional message flow (Transaction).It should be noted that the EPS Bearer ID may be EPS beareridentification information for identifying a dedicated bearer.Therefore, the EPS bearer ID may be identification information foridentifying an EPS bearer different from a default bearer. The TFTindicates all packet filters associated with the EPS bearer. The TFT isinformation for identifying a part of user data to be transmitted and/orreceived, and the UE_A10 uses the EPS bearer associated with the TFT totransmit and/or receive the user data identified by the TFT. In otherwords, the UE_A10 uses an RB (Radio Bearer) associated with the TFT totransmit and/or receive the user data identified by the TFT. Inaddition, the TFT may associate the user data such as application datato be transmitted and/or received with an appropriate transfer path, andmay be identification information for identifying application data. Inaddition, the UE_A10 may use the default bearer to transmit and/orreceive user data which cannot be identified by the TFT. In addition,the UE_A10 may store in advance the TFT associated with the defaultbearer.

The Default Bearer is EPS bearer identification information foridentifying a default bearer associated with a PDU session. It should benoted that the EPS bearer may be a logical communication pathestablished between the UE_A10 and the PGW_A30/UPGW_A130/UPF_A235, or acommunication path constituting a PDN connection/PDU session. Further,the EPS bearer may be a default bearer or a dedicated bearer.Furthermore, the EPS bearer may include an RB established between theUE_A10 and the base station and/or the access point within the accessnetwork. Moreover, the RB and the EPS bearer may be associated with eachother on a one-to-one basis. Therefore, identification information ofthe RB and identification information of the EPS bearer may beassociated with each other on a one-to-one basis, or may be the sameidentification information. It should be noted that the RB may be an SRBand/or a CRB, or a DRB. Furthermore, the Default Bearer may beinformation that the UE_A10 and/or the SGW_A35 and/or thePGW_A30/UPGW_A130/SMF_A230/UPF_A235 acquire from the core network at thetime when a PDU session is established. It should be noted that thedefault bearer is an EPS bearer initially established in a PDNconnection/PDU session, and is an EPS bearer that can be establishedonly once in one PDN connection/PDU session. The default bearer may alsobe an EPS bearer that can be used for communication of user data that isnot associated with the TFT. In addition, the dedicated bearer is an EPSbearer established after a default bearer is established in a PDNconnection/PDU session, and is an EPS bearer that can be establishedmultiple times during one PDN connection/PDU session. The dedicatedbearer is an EPS bearer that can be used for communication of user dataassociated with the TFT.

A User Identity is information for identifying a subscriber. The UserIdentity may be an IMSI or an MSISDN. Further, the User Identity mayalso be identification information other than the IMSI or the MSISDN.Serving Node Information is information for identifying theMME_A40/CPF_A140/AMF_A240 used in a PDU session, and may be an IPaddress of the MME_A40/CPF_A140/AMF_A240.

The eNB address is an IP address of the eNB_A45. The eNB ID isinformation for identifying the UE in the eNB_A45. An MME address is anIP address of the MME_A40/CPF_A140/AMF_A240. An MME ID is informationfor identifying the MME_A40/CPF_A140/AMF_A240. The NR node address is anIP address of the NR node_A122. The NR node ID is information foridentifying the NR node_A122. The WAG address is an IP address of a WAG.The WAG ID is information for identifying a WAG.

The anchor or anchor point is a UFP that functions as a gateway for DNand PDU sessions. The UPF serving as an anchor point may also be a PDUsession anchor or an anchor.

The SSC mode indicates a mode of Session and Service Continuitysupported by the system and/or each apparatus in the 5GC. Morespecifically, the SSC mode may be a mode indicating a type of Sessionand Service Continuity supported by a PDU session established betweenthe UE_A10 and the anchor point. Here, the anchor point may be eitherthe UPGW or the UPF_A235. Besides, the SSC mode may be a mode indicatinga type of Session and Service Continuity configured for each PDUsession. Further, the SSC mode may include three modes, i.e., an SSCmode 1, an SSC mode 2, and an SSC mode 3. The SSC mode is associatedwith the anchor point and cannot be changed while the PDU session isestablished.

In addition, the SSC mode 1 of the present embodiment is a mode ofSession and Service Continuity in which, when the UE_A10 connects to anetwork, the same UPF is continuously maintained as an anchor pointregardless of access technologies, such as the RAT (Radio AccessTechnology) and the cell, used. More specifically, the SSC mode 1 may bea mode that achieves the Session and Service Continuity without changingthe anchor point used by the established PDU session even in a case thatthe mobility of the UE_A10 occurs.

Further, the SSC mode 2 of the present embodiment is a mode of Sessionand Service Continuity in which, when an anchor point associated withone SSC mode 2 is included in the PDU session, the PDU session is firstreleased and then another PDU session is established. More specifically,the SSC mode 2 is a mode in which, when relocation of the anchor pointoccurs, the PDU session is deleted once and then a new PDU session isestablished.

Furthermore, the SSC mode 2 is a mode of Session and Service Continuityin which the same UPF is continuously maintained as the anchor pointonly within a serving area of the UPF. More specifically, the SSC mode 2may be a mode that achieves the Session and Service Continuity withoutchanging the UPF used by the established PDU session as long as theUE_A10 is within the serving area of the UPF. In addition, the SSC mode2 may be a mode that achieves the Session and Service Continuity bychanging the UPF used by the established PDU session when the mobilityof the UE_A10, such as the UE_A10 leaving the serving area of the UPF,occurs.

Here, a TUPF serving area may be an area in which one UPF can provide aSession and Service Continuity function, or a subset of the accessnetwork, such as a RAT or a cell, used when the UE_A10 connects to anetwork. Further, the subset of the access network may be a networkincluding one or more RATs and/or cells, or may be a TA.

Furthermore, the SSC mode 3 of the present embodiment is a mode ofSession and Service Continuity in which another PDU session can beestablished between a new anchor point and the UE for the same DNwithout releasing the PDU session between the UE and the anchor point.

Moreover, the SSC mode 3 is a mode of Session and Service Continuitythat allows a new PDU session and/or communication path to beestablished via a new UPF for the same DN before disconnecting the PDUsession and/or the communication path established between the UE_A10 andthe UPF. In addition, the SSC mode 3 may be a mode of Session andService Continuity that allows the UE_A10 to be multi-homed.

Additionally/alternatively, the SSC mode 3 may be a mode of Session andService Continuity in which the use of multiple PDU sessions and/or theUPFs associated with the PDU sessions may be permitted. In other words,in the case of the SSC mode 3, each apparatus may achieve the Sessionand Service Continuity by using a plurality of PDU sessions, or mayachieve the Session and Service Continuity by using a plurality ofTUPFs.

Here, when each apparatus establishes a new PDU session and/orcommunication path, a new UPF may be selected by the network, or a newUPF may be an optimal UPF for a place at which the UE_A10 connects tothe network. Further, when the multiple PDU sessions and/or the UPFsused by the PDU sessions are valid, the UE_A10 may correlate applicationand/or flow communications to newly established PDU sessionsimmediately, or may implement it based on the completion of thecommunications.

[1.3. Description of Initial Procedure]

Next, before the detailed procedure of an initial procedure in thepresent embodiment is described, in order to avoid duplicatedescriptions, terminology specific to the present embodiment and primaryidentification information used in each procedure will be described inadvance.

In the present embodiment, a network refers to at least some of theaccess network_A20/80, the access network_B80/120, the core network_A90,the core network_B190, the DN_A5, and the PDN_A6. In addition, one ormore apparatuses included in at least some of the access network_A20/80,the access network_B80/120, the core network_A90, the core network_B190,the DN_A5, and the PDN_A6 may also be referred to as a network or anetwork apparatus. In other words, the expression that a networkperforms transmission and/or reception of a message and/or performs aprocedure means that an apparatus (network apparatus) within a networkperforms transmission and/or reception of a message and/or performs aprocedure.

A session management (SM) message (also referred to as aNon-Access-Stratum (NAS) SM message or an SM message) of the presentembodiment may be a NAS message used in a procedure for SM (alsoreferred to as a session management procedure or an SM procedure), ormay be a control message transmitted and/or received between the UE_A10and the SMF_A230 via the AMF_A240. Further, the SM message may include aPDU session establishment request message, a PDU session establishmentaccept message, a PDU session complete message, a PDU session rejectmessage, a PDU session modification request message, a PDU sessionmodification accept message, a PDU session modification reject message,and the like. In addition, the procedure for SM may include a PDUsession establishment procedure, a PDU session modification procedure,and the like.

In the present embodiment, a tracking area (also referred to as TA) is arange that can be represented by location information of the UE_A10managed by the core network, and may include, for example, one or morecells. In addition, the TA may be a range in which a control messagesuch as a paging message is broadcasted, or a range in which the UE_A10can move without performing a handover procedure.

In the present embodiment, a TA list is a list including one or more TAsallocated to the UE_A10 by the network. In addition, while the UE_A10 ismoving within the one or more TAs included in the TA list, the UE_A10can move without performing a registration procedure. In other words,the TA list may be an information group indicating an area in which theUE_A10 can move without performing a registration procedure.

In the present embodiment, a network slice (NS) is a logical networkthat provides a specific network capability and a networkcharacteristic. Hereinafter, the network slice will also be referred toas an NW slice.

A network slice instance (NSI) of the present embodiment is an entity ofeach of one or more network slices configured in the core network_B190.In addition, the NSI in the present embodiment may include a virtual NF(Network Function) generated by using an NST (Network Slice Template).Here, the NST is associated with a resource request for providing arequired communication service or capability, and is a logicalexpression of one or more NFs (Network Functions). In other words, theNSI may be an aggregation including a plurality of NFs in the corenetwork_B190. In addition, the NSI may be a logical network configuredto classify user data delivered through a service or the like. Thenetwork slice may include at least one or more NFs. The NF included inthe network slice may or may not be an apparatus shared by anothernetwork slice. The UE_A10 and/or an apparatus within a network can beallocated to one or more network slices based on NSSAI and/or S-NSSAIand/or UE usage type and/or one or more network slice type IDs, and/orone or more NS IDs of registration information, and/or the APN.

The S-NSSAI of the present embodiment is an abbreviation for SingleNetwork Slice Selection Assistance information, and is information foridentifying a network slice. The S-NSSAI may include an SST(Slice/Service type) and an SD (Slice Differentiator). The S-NSSAI mayinclude only an SST or both an SST and an SD. Here, the SST isinformation indicating an operation of a network slices expected interms of function and service. Also, the SD may be informationcomplementing the SST at the time when one NSI is selected from aplurality of NSIs indicated by the SST. The S-NSSAI may be informationunique for each PLMN (Public Land Mobile Network), or may be standardinformation common among PLMNs, or may be information unique for eachtelecommunication operator which differs for each PLMN.

More specifically, the SST and/or the SD may be standard information(Standard Value) that is common among PLMNs, or may be information(Non-Standard Value) that is unique for each telecommunication operatorwhich is differs for each PLMN. In addition, the network may store oneor more pieces of S-NSSAI in the registration information of the UE_A10as default S-NSSAI.

NSSAI (Network Slice Selection Assistance Information) of the presentembodiment is a group of S-NSSAI (Single Network Slice SelectionAssistance Information). Each piece of S-NSSAI included in the NSSAI isinformation assisting the access network or the core network to selectan NSI. The UE_A10 may store the NSSAI allowed from the network for eachPLMN. Furthermore, the NSSAI may be information used to select theAMF_A240.

An operator A network of the present embodiment is a network operated bya network operator A (operator A). Here, for example, the operator A maydeploy a common NW slice that is shared by an operator B which will bedescribed below.

An operator B network of the present embodiment is a network operated bya network operator B (operator B). Here, for example, the operator B maydeploy a common NW slice that is shared by the operator A.

A first NW slice of the present embodiment is an NW slice to which anestablished PDU session belongs at the time when the UE connects to aparticular DN. It should be noted that, for example, the first NW slicemay be an NW slice that is managed within the operator A network, or anNW slice that is commonly managed in the operator B network.

A second NW slice of the present embodiment is an NW slice which anotherPDU session belongs to and which is capable of connecting to the DNserving as a connection destination of the PDU session belonging to thefirst NW slice. It should be noted that the first NW slice and thesecond NW slice may be operated by the same operator or may be operatedby different operators.

In the present embodiment, an equivalent PLMN refers to a PLMN treatedto be the same PLMN as any PLMN in the network.

A DCN (Dedicated Core Network) of the present embodiment is one or morespecific subscriber-type dedicated core networks configured in the corenetwork_A90. More specifically, a DCN for UE registered as a user of anM2M (Machine to Machine) communication function may be configured, forexample, in the core network_A90. In addition, a default DCN for UEwithout a proper DCN may be configured within the core network_A90.Further, at least one or more MMEs_40 or SGSNs_A42 may be deployed in aDCN, and further, at least one or more SGWs_A35, PGWs_A30, or PCRFs_A60may be deployed in the DCN. It should be noted that the DCN may beidentified with a DCN ID, and further the UE may be assigned to one DCNbased on information such as a UE usage type and/or the DCN ID.

A first timer of the present embodiment is a timer to initiate aprocedure for session management, such as a PDU session establishmentprocedure, and/or to manage transmission of an SM (Session Management)message, such as a PDU session establishment request message, and may beinformation indicating a value of a back-off timer for managing sessionmanagement behaviors. Hereinafter, the first timer and/or the back-offtimer may be referred to as a timer. While the first timer is running,each apparatus may be prohibited from initiating a procedure for sessionmanagement and/or transmitting and receiving an SM message. It should benoted that the first timer may be configured to be associated with atleast one of a unit of congestion management applied by an NW and/or aunit of congestion management identified by a UE. For example, the firsttimer may be configured for at least one of a unit of APN/DNN, and/or aunit of identification information indicating one or more NW slices,and/or a unit of reject cause value in a session management procedure,and/or a unit of session indicated to be rejected in a sessionmanagement procedure, and/or a unit of PTI of a session managementprocedure.

It should be noted that an SM message may be an NAS message used in aprocedure for session management and may be a control messagetransmitted and/or received between the UE_A10 and the SMF_A230 via theAMF_A240. Further, the SM message may include a PDU sessionestablishment request message, a PDU session establishment acceptmessage, a PDU session complete message, a PDU session reject message, aPDU session modification request message, a PDU session modificationaccept message, a PDU session modification reject message, and the like.Furthermore, the procedure for session management may include a PDUsession establishment procedure, a PDU session modification procedure,and the like. In addition, in these procedures, a back-off timer valuemay be included for each message received by the UE_A10. The UE may seta back-off timer received from the NW as a first timer, may set thefirst timer to a timer value in another method, or may set the firsttimer to a random value. In addition, when a plurality of back-offtimers received from the NW are included, the UE may manage a pluralityof “first timers” according to the plurality of back-off timers, or mayselect one timer value from the plurality of back-off timer valuesreceived from the NW based on a policy held by the UE so as to set thefirst timer to the one time value and manage the first timer. Forexample, when two back-off timer values are received, the UE sets the“first timer #1” and the “first timer #2” respectively to the back-offtimer values received from the NW and manage the “first timer #1” andthe “first timer #2”. Besides, one value may be selected from theplurality of back-off timer values received from the NW based on thepolicy held by the UE, and the first timer is set to the one value andmanaged.

When the UE_A10 receives a plurality of back-off timer values from theNW, the UE_A10 may manage a plurality of “first timers” according to theplurality of back-off timers. Here, in order to distinguish theplurality of “first timers” received by the UE_A10, they may bedescribed, for example, as the “first timer #1” or the “first timer #2.”It should be noted that the plurality of back-off timers may be acquiredin a single session management procedure, or may be acquired indifferent session management procedures.

Here, the first timer may be a back-off timer for suppressingreconnection and configured for multiple related NW slices based oninformation for identifying one NW slice as previously described, or maybe a back-off timer for preventing reconnection and configured for aunit of a combination of an APN/DNN and one NW slice, but is not limitedthereto, and the first timer may be a back-off timer for suppressingreconnection and configured for a unit of a combination of an APN/DNNand multiple related NW slices based on information for identifying oneNW slice.

Re-attempt information included in the 11th identification informationin the present embodiment is information indicated by a network (NW) tothe UE_A10 whether to allow reconnection using the same DNN informationand/or S-NSAI information for a PDU session establishment request(S1100) that is rejected.

At this time, in the PDU session establishment request (1100), when theUE performs the PDU session establishment request (S1100) including noDNN, the information including no DNN is referred to as the sameinformation. In addition, in the PDU session establishment request(1100), when the UE performs the PDU session establishment request(S1100) including no S-NSSAI, the information including no S-NSSAI isreferred to as the same information.

It should be noted that the re-attempt information may be configured ina UTRAN access unit, and/or an E-UTRAN access unit, and/or an NR accessunit, and/or a piece of slice information unit, and/or an equivalentPLMN unit, and/or an S1 mode unit, and/or an NW mode unit.

Further, the re-attempt information specified in an access unit (a UTRANaccess, an E-UTRAN access, or an NR access) may be informationindicating reconnection using the same information for the network onthe premise of an access change. Further, the re-attempt informationspecified in a slice unit may be specified as slice informationdifferent from information for a rejected slice, and reconnection usingthe specified slice information may be allowed.

Further, the re-attempt information specified in an equivalent PLMN unitmay be information indicating that when a PLMN is changed, reconnectionusing the same information is allowed if the changed PLMN is anequivalent PLMN. In addition, if the changed PLMN is not an equivalentPLMN, the re-attempt information may be information indicating thatreconnection using the present procedure is not allowed.

Further, the re-attempt information specified in a mode unit (S1 mode orN1 mode) may be information indicating that when a mode is changed,reconnection using the same information is allowed if the changed modeis an S1 mode. In addition, as long as the changed mode is the S1 mode,the re-attempt information may also be information indicating thatreconnection using the same information is not allowed.

A network slice association rule of the present embodiment is a rule forassociating information that identifies a plurality of network slices.It should be noted that the network slice association rule may bereceived in a PDU session reject message or may be preconfigured in theUE_A10. In addition, for the network slice association rules, the latestone may be applied in the UE_A10. Conversely, the UE_A10 may behavebased on the latest network slice association rule. For example, whenthe UE_A10 receives a new network slice association rule in the PDUsession reject message with a network slice association rulepreconfigured in the UE_A10, the UE_A10 may update the network sliceassociation rule held in the UE_A10.

A priority management rule of the back-off timer of the presentembodiment is a rule configured for the UE_A10 to collectively manage aplurality of back-off timers that have occurred in a plurality of PDUsessions on a single back-off timer. For example, when conflicting oroverlapping congestion management is applied and the UE holds aplurality of back-off timers, the UE_A10 may collectively manage theplurality of back-off timers based on the priority management rules ofthe back-off timers. It should be noted that a pattern in whichconflicting or overlapping congestion management occurs is a case thatcongestion management based only on a DNN and congestion managementbased both on the DNN and slice information are applied at the sametime, and in this case, congestion management based only on the DNN isprioritized. It should be noted that the priority management rules ofthe back-off timers may not be limited to the above. It should be notedthat the back-off timer may be a first timer included in the PDU sessionreject message.

A first state of the present embodiment is a state in which eachapparatus has completed a registration procedure and a PDU sessionestablishment procedure, and the UE_A10 and/or each apparatus is in astate in which one or more of the congestion managements from the firstcongestion management to the fourth congestion management have beenapplied. Here, the UE_A10 and/or each apparatus may be in a state inwhich the UE_A10 has been registered in the network (the RM-REGISTEREDstate) after the completion of the registration procedure, and the statein which the PDU session establishment procedure has been completed maybe a state in which the UE_A10 has received a PDU session establishmentreject message from the network.

The congestion management of the present embodiment includes one or morecongestion managements from the first congestion management to thefourth congestion management. It should be noted that the control of theUE by the NW is achieved by congestion management recognized by the UEand the first timer, and the UE may store the association of theseinformation.

The first congestion management of the present embodiment indicatescontrol signal congestion management directed to a DNN parameter. Forexample, when congestion on a DNN #A is detected in an NW and the NWrecognizes it as a UE-initiated session management request directed onlyto a DNN #A parameter, the NW can apply the first congestion management.It should be noted that even when the UE-initiated session managementrequest does not include DNN information, the NW may select a defaultDNN initiated by the NW and configure it as a target subjected tocongestion management. Alternatively, even when the NW recognizes it asa UE-initiated session management request including the DNN #A andS-NSSAI #A, the NW may apply the first congestion management. When thefirst congestion management is applied, the UE may suppress theUE-initiated session management request directed only to the DNN #A.

In other words, the first congestion management of the presentembodiment is control signal congestion management directed to the DNN,and may be congestion management caused by connectivity to the DNN in acongestion state. For example, the first congestion management may becongestion management to restrict connection to the DNN #A in all typesof connectivity. Here, the connection to the DNN #A in all types ofconnectivity may be a connection to the DNN #A in connectivity using alltypes of S-NSSAI available for the UE, and may be a connection to theDNN #A through a network slice to which the UE can connect. Furthermore,connectivity to the DNN #A without passing through a network slice maybe included.

The second congestion management of the present embodiment indicatescontrol signal congestion management directed to an S-NSSI parameter.For example, when control signal congestion with respect to S-NSSAI #Ais detected in an NW and the NW recognizes it as a UE-initiated sessionmanagement request directed only to an S-NSSAI #A parameter, the NW mayapply the second congestion management. When the second congestionmanagement is applied, the UE may suppress the UE-initiated sessionmanagement request directed only to the S-NSSAI #A.

In other words, the second congestion management of the presentembodiment is control signal congestion management directed to theS-NSSAI, and may be congestion management caused by a network sliceselected based on the S-NSSAI in a congestion state. For example, thesecond congestion management may be congestion management to restrictall connections based on the S-NSSAI #A. In other words, the secondcongestion management may be congestion management to restrict allconnections to the DNN via a network slice selected based on the S-NSSAI#A.

The third congestion management of the present embodiment indicatescontrol signal congestion management directed to DNN and S-NSSAIparameters. For example, when control signal congestion with respect toDNN #A and control signal congestion with respect to S-NSSAI #A aredetected at the same time in an NW and when the NW recognizes it as aUE-initiated session management request directed to DNN #A and S-NSSAI#A parameters, the NW may apply the third congestion management. Itshould be noted that even when the UE-initiated session managementrequest does not include information indicating the DNN, the NW mayselect a default DNN initiated by the NW and configure it as a targetsubjected to congestion management. When the third congestion managementis applied, the UE may suppress the UE-initiated session managementrequest directed to the DNN #A and S-NSSAI #A parameters.

In other words, the third congestion management of the presentembodiment is control signal congestion management directed to the DNNand S-NSSAI parameters, and may be congestion management caused byconnectivity to the DNN via a network slice selected based on theS-NSSAI in a congestion state. For example, the third congestionmanagement may be congestion management to restrict a connection to theDNN #A in connectivity based on the S-NSSAI #A.

The fourth congestion management of the present embodiment indicatescontrol signal congestion management directed to at least one of DNNand/or S-NSSAI parameters. For example, when control signal congestionwith respect to DNN #A and control signal congestion with respect toS-NSSAI #A are detected at the same time in an NW and when the NWrecognizes it as a UE-initiated session management request directed toat least one of DNN #A and/or S-NSSAI #A parameters, the NW may applythe fourth congestion management. It should be noted that even when theUE-initiated session management request does not include informationindicating the DNN, the NW may select a default DNN initiated by the NWand configure it as a target subjected to congestion management. Whenthe fourth congestion management is applied, the UE suppresses theUE-initiated session management request directed to at least one of theDNN #A and/or S-NSSAI #A parameters.

In other words, the fourth congestion management of the presentembodiment is control signal congestion management directed to the DNNand S-NSSAI parameters, and may be congestion management caused by anetwork slice selected based on the S-NSSAI and by connectivity to theDNN in a congestion state. For example, the fourth congestion managementmay be congestion management to restrict all connections based on theS-NSSAI #A and may be congestion management to restrict a connection tothe DNN #A in all types of connectivity. In other words, the fourthcongestion management may be congestion management to restrict allconnections to the DNN via a network slice selected based on the S-NSSAI#A and may be congestion management to restrict a connection to the DNN#A in all types of connectivity. Here, the connection to the DNN #A inall types of connectivity may be a connection to the DNN #A inconnectivity using all types of S-NSSAI available for the UE, and may bea connection to the DNN #A through a network slice to which the UE canconnect. Furthermore, connectivity to the DNN #A without passing througha network slice may be included.

Therefore, the fourth congestion management having the DNN #A and theS-NSSAI #A as parameters may be congestion management in which the firstcongestion management having the DNN #A as a parameter and the secondcongestion management having the S-NSSAI #A as a parameter aresimultaneously performed.

A first behavior of the present embodiment is a behavior the UE storingthe slice information transmitted in a first PDU session establishmentrequest message in association with transmitted PDU sessionidentification information. In the first behavior, the UE may store theslice information transmitted in the first PDU session establishmentrequest message or may store the slice information received at the timewhen the first PDU session establishment request is rejected.

A second behavior of the present embodiment is a behavior of the UEtransmitting a PDU session establishment request for connecting to thesame APN/DNN as the first PDU session establishment request by usinganother piece of slice information different from the slice informationspecified in the first PDU session establishment. Specifically, thesecond behavior may be a behavior in which when a back-off timer valuereceived from a network is zero or invalid, the UE transmits a PDUsession establishment request for connecting to an APN/DNN, which is thesame as the APN/DNN for which the first PDU session establishmentrequest is transmitted, by using another piece of slice informationdifferent from the slice information specified in the first PDU sessionestablishment. Alternatively, the second behavior may be a behavior inwhich when the first PDU session is rejected because radio access of aspecific PLMN to which a specified APN/DNN is connected is notsupported, or when a first PDU session is rejected because of atemporary cause, the UE transmits a PDU session establishment requestfor connecting to an APN/DNN, which is the same as the APN/DNN includedin the first PDU session establishment request, by using another pieceof slice information different from the slice information specified inthe first PDU session establishment.

A third behavior of the present embodiment is a behavior of the UEtransmitting no new PDU session establishment request that uses the sameidentification information until the first timer expires when the PDUsession establishment request is rejected. Specifically, the thirdbehavior may also be a behavior of the UE transmitting no new PDUsession establishment request that uses the same identificationinformation until the first timer expires when a back-off timer valuereceived from the network is neither zero nor invalid. Here, the sameidentification information may mean that the first identificationinformation and/or the second identification information included in anew PDU session establishment request are the same, or may mean that thefirst identification information and/or the second identificationinformation transmitted in a rejected PDU session establishment requestare the same.

In addition, the third behavior may also be a behavior of the UEtransmitting no new PDU session establishment request that uses the sameidentification information until the first timer expires in a case thatanother PLMN is selected or another NW slice is selected, a reject causefor a configuration failure for network operations is received, and aback-off timer received is activated when the first PDU sessionestablishment request is rejected.

In more detail, a PDU session of which a new PDU session establishmentrequest in the third behavior is not transmitted may be a PDU session towhich congestion management associated with the first timer is applied.More specifically, the third behavior may be a behavior of transmittingno new PDU session establishment request for a PDU session that is withconnectivity depending on a type of congestion management associatedwith the first timer and uses the DNN and/or the S-NSSAI associated withthe congestion management. It should be noted that processing of the UEto be prohibited by the present behavior may be an initiation of aprocedure for session management including a PDU session establishmentrequest and/or transmission and/or reception of an SM message.

A fourth behavior of the present embodiment is a behavior of the UEtransmitting no new PDU session establishment request that does notcarry slice information and DNN/APN information until the first timerexpires when a PDU session establishment request is rejected.Specifically, the fourth behavior may be a behavior of the UEtransmitting no new PDU session establishment request that does notcarry the slice information and the DNN/APN information until the firsttimer expires when a back-off timer received from the network is neitherzero nor invalid.

The fifth behavior of the present embodiment is a behavior of the UEtransmitting no new PDU session establishment request that uses the sameidentification information when the PDU session establishment request isrejected. Specifically, the fifth behavior may be a behavior of the UEtransmitting no new PDU session establishment request that uses the sameidentification information in a case that the UE is located in anequivalent PLMN when PDP types supported by the UE and the network aredifferent.

A sixth behavior of the present embodiment is a behavior of the UEtransmitting a new PDU session establishment request as an initialprocedure using the same identification information when the PDU sessionestablishment request is rejected. Specifically, the sixth behavior maybe a behavior of the UE transmitting a new PDU session establishmentrequest as an initial procedure using the same identificationinformation in a case that a first PDU session establishment request isrejected because no targeted PDN session context exists in a handoverfrom a non-3GPP access.

A seventh behavior of the present embodiment is a behavior of the UEcontinuing a back-off timer received at the time when a previous PDUsession establishment request was rejected in a case that another NWslice is selected in a procedure for selecting the PLMN. Specifically,the seventh behavior is a behavior of the UE continuing a back-off timerreceived at the time when the first PDU session establishment requestwas rejected in a case that a PLMN is selected at the time when thefirst PDU session establishment request is rejected and that a NW slicecommon to the NW slice specified in the first PDU session establishmentrequest can be specified in the selected PLMN.

An eighth behavior of the present embodiment is a behavior of the UEconfiguring a value notified from a network or a value preconfigured inthe UE as a first timer value. Specifically, the eighth behavior may bea behavior of the UE configuring a back-off timer value received in arejection notification for the first PDU session establishment requestas the first timer value, or may be a behavior of configuring a valuepreconfigured or held in the UE as the first timer value. In addition,the eighth behavior of configuring a timer preconfigured or held in theUE as the first timer value may be limited to a case that the UE islocated in an HPLMN or an equivalent PLMN.

A ninth behavior of the present embodiment is a behavior of the UEtransmitting no new PDU session establishment request until the terminalpower is turned on/off or a USIM (Universal Subscriber Identity Module)is inserted/removed when the PDU session establishment request isrejected. Specifically, in the ninth behavior, the UE transmits no newPDU session establishment request until the terminal power is turnedon/off or the USIM is inserted/removed in a case that a back-off timerreceived from a network is invalid or in a case that a first PDU sessionreject cause is that the PDP types between the UE and the network aredifferent. Alternatively, the ninth behavior may be a behavior oftransmitting no new PDU session establishment request until the terminalpower is turned on/off or the USIM is inserted/removed in a connectedPLMN in a case that the first PDU session is rejected because aspecified APN/DNN is not supported wirelessly by a connected PLMN, andthat there is no back-off timer information element from the network andthere is no Re-attempt information, or in a case that PDU sessionreconnection to an equivalent PLMN is allowed. Alternatively, the ninthbehavior may be a behavior of transmitting no new PDU sessionestablishment request until the terminal power is turned on/off or theUSIM is inserted/removed in a connected PLMN in a case that the firstPDU session is rejected because a specified APN/DNN is not supportedwirelessly by a connected PLMN, there is no back-off timer informationelement from the network, and there is no Re-attempt information, or ina case that PDU session reconnection to an equivalent PLMN is notallowed. Alternatively, the ninth behavior may be a behavior oftransmitting no new PDU session establishment request until the terminalpower is turned on/off or the USIM is inserted/removed in a case thatthe first PDU session is rejected because a specified APN/DNN is notsupported wirelessly by a connected PLMN, and in a case that a back-offtimer from the network is neither zero nor invalid. Alternatively, theninth behavior may be a behavior of transmitting no new PDU sessionestablishment request until the terminal power is turned on/off or theUSIM is inserted/removed in a case that the first PDU session isrejected because a specified APN/DNN is not supported wirelessly by aconnected PLMN, and in a case that a back-off timer from the network isinvalid.

The tenth behavior of the present embodiment is a behavior of the UEtransmitting a new PDU session establishment request when the PDUsession establishment request is rejected. Specifically, the tenthbehavior may be a behavior of the UE transmitting a new PDU sessionestablishment request in a case that a back-off timer received from thenetwork is zero or that the first PDU session establishment request isrejected due to a temporary cause, and that there is no back-off timerinformation element itself notified from the network. Alternatively, thetenth behavior may be a behavior of transmitting a new PDU sessionestablishment request in a case that another PLMN is selected or anotherNW slice is selected, that the first PDU session establishment requestis rejected due to a temporary cause, that the back-off timer has notactivated for a targeted APN/DNN in the selected PLMN, or that theback-off timer received from the network is invalid. Alternatively, thetenth behavior may be a behavior of transmitting a new PDU sessionestablishment request in a case that the first PDU session establishmentrequest is rejected due to different PDP types of the UE and thenetwork, and in a case that Re-attempt information is not received atthe time when a different PLMN is selected, or that a PLMN that is notin an equivalent PLMN list is selected, or that a PDP type is changed,or that the terminal power is turned on/off or the USIM isinserted/removed. Alternatively, the tenth behavior may be a behavior oftransmitting a new PDU session establishment request in a case that thefirst PDU session is rejected because a specified APN/DNN is notsupported wirelessly by a connected PLMN, and in a case that a back-offtimer notified and received from the network is zero.

An 11th behavior of the present embodiment is a behavior of the UEignoring the first timer and the Re-attempt information. Specifically,the 11th behavior may be a behavior of the UE ignoring the first timerand the Re-attempt information in a case that the first PDU sessionestablishment request is rejected because no targeted PDN sessioncontext exists in handover from a non-3GPP access, or in a case that thefirst PDU session establishment is rejected because the number ofbearers established in a PDN connection reaches a maximum number.

A 12th behavior of the present embodiment is a behavior of the UEdetermining information for identifying multiple related NW slices basedon information for identifying one NW slice received in a rejectionnotification for the first PDU session establishment request, and is thebehavior of the UE suppressing reconnection to the multiple related NWslices based on information for identifying one NW slice. Specifically,the 12th behavior may be a behavior of the UE deriving information foridentifying another NW slice relevant to information for identifying anNW slice notified in the rejection of the first PDU sessionestablishment request based on a network slice related rule. It shouldbe noted that the network slice related rule may be preconfigured in theUE or may be notified from the network in a rejection notification forthe PDU session establishment.

A 13th behavior of the present embodiment may be a behavior of the UEmanaging a timer based on a priority management rule of the back-offtimer in a case that a plurality of different congestion managements areactivated by the same UE for one or more PDU session establishments andthat a plurality of timers are provided from the network. For example,the first PDU session establishment request made by the UE for acombination of a DNN_1 and a slice_1 is subjected to congestionmanagement based on both the DNN and slice information, and the UEreceives a first timer #1. In addition, the UE makes a second PDUsession establishment request for a combination of a DNN_1 and aslice_2, subjected to congestion management based only on the DNN, andreceives a first timer #2. At this time, the UE may manage a behavior ofthe UE re-establishing a PDU session through the dominant first timer #2based on a priority management rule of the back-off timer. Specifically,a timer value held by the UE may be overwritten with a timer valuegenerated by a prioritized congestion control.

A 14th behavior of the present embodiment may be a behavior of managinga timer for each session management instance (on a per PDU sessionbasis) in a case that a plurality of different congestion managementsare applied by the same UE for one or more PDU session establishmentsand that a plurality of timers are provided from the network. Forexample, when the first PDU session establishment made by the UE for thecombination of the DNN #1 and the slice #1 is subjected to congestionbased on both the DNN and slice information, the UE manages a targetback-off timer value as the first timer #1. Thereafter, when the UEfurther attempts to establish a PDU session for a combination of the DNN#1 and a slice #2 as a second PDU session, subjected to congestion basedonly on the DNN, the UE manages the target back-off timer value as thefirst timer #2. At this time, the UE simultaneously manages a pluralityof timers (here, the first timer #1 and the first timer #2).Specifically, the UE manages the timer on a per session managementinstance/PDU session basis. In addition, when the UE receives aplurality of timers simultaneously in one session management procedure,the UE simultaneously manages the target back-off timer based on acongestion management unit identified by the UE.

A 15th behavior in the present embodiment may be a behavior of the UEperforming a first identification process to identify which type ofcongestion management to apply among the congestion managements from thefirst congestion management to the fourth congestion management andperforming a second identification process to identify the DNN and/orthe S-NSSAI associated with the applied congestion management. It shouldbe noted that the first identification process may be performed based onat least one piece of identification information from the firstidentification information to the fourth identification informationand/or at least one piece of identification information from 11thidentification information to 18th identification information.Similarly, the second identification process may be performed based onat least one piece of identification information from the firstidentification information to the fourth identification informationand/or at least one piece of identification information from 11thidentification information to 18th identification information.

An example of a first identification process will be described below. Inthe first identification process, the type of applied congestionmanagement may be identified as first congestion management when any oneof or two or more combinations of the following cases are met.

-   -   A case that at least 15th identification information is a value        corresponding to the first congestion management.    -   A case that at least 16th identification information is a value        corresponding to the first congestion management.    -   A case that at least 14th identification information includes        information indicating the first congestion management.    -   A case that at least 17th identification information includes        only the DNN and does not include the S-NSSAI.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        first congestion management and the second congestion management        and is information in which only a value corresponding to the        second congestion management is configurable for the 16th        identification information, and a case that at least the 16th        identification information is not received.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        first congestion management and the fourth congestion management        and is information in which only a value corresponding to the        fourth congestion management is configurable for the 16th        identification information, and a case that at least the 16th        identification information is not received.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        first congestion management, the second congestion management        and the fourth congestion management and is information in which        only a value corresponding to the second congestion management        and a value corresponding to the fourth congestion management        are configurable for the 16th identification information, and a        case that at least the 16th identification information is not        received.

However, the present embodiment is not limited to the example describedabove, and the UE_A10 may perform the identification process based on atleast one piece of identification information from the firstidentification information to the fourth identification information,and/or based on at least one piece of identification information or acombination of two or more pieces of identification information from the11th identification information to the 18th identification information.

In the first identification process, the type of applied congestionmanagement may be identified as second congestion management when anyone of or two or more combinations of the following cases are met.

-   -   A case that at least 15th identification information is a value        corresponding to the second congestion management.    -   A case that at least 16th identification information is a value        corresponding to the second congestion management.    -   A case that at least 14th identification information includes        information indicating the second congestion management.    -   A case that at least the 17th identification information        includes only the S-NSSAI and does not include the DNN.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        first congestion management and the second congestion management        and is information in which only a value corresponding to the        first congestion management is configurable for the 16th        identification information, and a case that at least the 16th        identification information is not received.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        second congestion management and the third congestion management        and is information in which only a value corresponding to the        third congestion management is configurable for the 16th        identification information, and a case that at least the 16th        identification information is not received.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        second congestion management, the third congestion management        and the fourth congestion management and is information in which        only a value corresponding to the third congestion management        and a value corresponding to the fourth congestion management        are configurable for the 16th identification information, and a        case that at least the 16th identification information is not        received.

However, the present embodiment is not limited to the example describedabove, and the UE_A10 may perform the identification process based on atleast one piece of identification information from the firstidentification information to the fourth identification information,and/or based on at least one piece of identification information or acombination of two or more pieces of identification information from the11th identification information to the 18th identification information.

In the first identification process, the type of applied congestionmanagement may be identified as third congestion management when any oneof or two or more combinations of the following cases are met.

-   -   A case that at least 15th identification information is a value        corresponding to the third congestion management.    -   A case that at least 16th identification information is a value        corresponding to the third congestion management.    -   A case that at least 14th identification information includes        information indicating the third congestion management.    -   A case that at least the 15th identification information is a        value corresponding to a plurality of congestion managements        including the third congestion management and not including the        fourth congestion management, and that the 17th identification        information includes the S-NSSAI and DNN.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        third congestion management and the fourth congestion management        and is information in which only a value corresponding to the        fourth congestion management is configurable for the 16th        identification information, and a case that at least the 16th        identification information is not received.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        second congestion management and the third congestion management        and is information in which only a value corresponding to the        second congestion management is configurable for the 16th        identification information, and a case that at least the 16th        identification information is not received.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        second congestion management, the third congestion management        and the fourth congestion management and is information in which        only a value corresponding to the second congestion management        and a value corresponding to the fourth congestion management        are configurable for the 16th identification information, and a        case that at least the 16th identification information is not        received.

However, the present embodiment is not limited to the example describedabove, and the UE_A10 may perform the identification process based on atleast one piece of identification information from the firstidentification information to the fourth identification information,and/or based on at least one piece of identification information or acombination of two or more pieces of identification information from the11th identification information to the 18th identification information.

In the first identification process, the type of applied congestionmanagement may be identified as fourth congestion management when anyone of or two or more combinations of the following cases are met.

-   -   A case that at least 15th identification information is a value        corresponding to the fourth congestion management.    -   A case that at least 16th identification information is a value        corresponding to the fourth congestion management.    -   A case that at least 14th identification information includes        information indicating the fourth congestion management.    -   A case that at least the 15th identification information is a        value corresponding to a plurality of congestion managements        including the fourth congestion management and not including the        third congestion management, and that the 17th identification        information includes the S-NSSAI and DNN.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        third congestion management and the fourth congestion management        and is information in which only a value corresponding to the        third congestion management is configurable for the 16th        identification information, and a case that at least the 16th        identification information is not received.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        second congestion management and the fourth congestion        management and is information in which only a value        corresponding to the second congestion management is        configurable for the 16th identification information, and a case        that at least the 16th identification information is not        received.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        first congestion management and the fourth congestion management        and is information in which only a value corresponding to the        first congestion management is configurable for the 16th        identification information, and a case that at least the 16th        identification information is not received.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        second congestion management, the third congestion management        and the fourth congestion management and is information in which        only a value corresponding to the second congestion management        and a value corresponding to the third congestion management are        configurable for the 16th identification information, and a case        that at least the 16th identification information is not        received.    -   A case that the 16th identification information is information        for identifying the identification information in any of the        first congestion management, the second congestion management        and the fourth congestion management and is information in which        only a value corresponding to the first congestion management        and a value corresponding to the second congestion management        are configurable for the 16th identification information, and a        case that at least the 16th identification information is not        received.

However, the present embodiment is not limited to the example describedabove, and the UE_A10 may perform the identification process based on atleast one piece of identification information from the firstidentification information to the fourth identification information,and/or based on at least one piece of identification information or acombination of two or more pieces of identification information from the11th identification information to the 18th identification information,or may perform the identification process by using other means.

As described above, a type of congestion management may be identified bythe first identification process.

Next, an example of a second identification process will be described.Besides, the second identification process may be a process foridentifying a corresponding DNN and/or S-NSSAI for the type ofcongestion management identified by the first identification process.

More specifically, the DNN corresponding to the first congestionmanagement, the third congestion management, and the fourth congestionmanagement may be determined based on 12th identification information.Additionally/alternatively, the DNN corresponding to the firstcongestion management, the third congestion management, and the fourthcongestion management may be determined based on 17th identificationinformation. Additionally/alternatively, the DNN corresponding to thefirst congestion management, the third congestion management, and thefourth congestion management may be determined based on 2ndidentification information.

Therefore, the DNN corresponding to the first congestion management, thethird congestion management, and the fourth congestion management may bea DNN indicated by the 12th identification information.Additionally/alternatively, the DNN corresponding to the firstcongestion management, the third congestion management, and the fourthcongestion management may be a DNN included in the 17th identificationinformation. Additionally/alternatively, the DNN corresponding to thefirst congestion management, the third congestion management, and thefourth congestion management may be a DNN indicated by the 2ndidentification information.

In addition, the S-NSSAI corresponding to the second congestionmanagement, the third congestion management, and the fourth congestionmanagement may be determined based on 17th identification information.Additionally/alternatively, the DNN corresponding to the firstcongestion management, the third congestion management, and the fourthcongestion management may be determined based on 1st identificationinformation.

Therefore, the DNN corresponding to the first congestion management, thethird congestion management, and the fourth congestion management may beS-NSSAI indicated by the 17th identification information.Additionally/alternatively, the DNN corresponding to the firstcongestion management, the third congestion management, and the fourthcongestion management may be S-NSSAI included in the 1st identificationinformation.

However, the present embodiment is not limited to the example describedabove, and the UE_A10 may also perform the identification process basedon at least one piece of identification information from the firstidentification information to the fourth identification information,and/or based on at least one piece of identification information or acombination of two or more pieces of identification information from the11th identification information to the 18th identification information,or may perform the identification process by using other means.

Based on the above 15th behavior, the UE_A10 may identify a congestionmanagement that the core network_B190 applies to the UE_A10. In otherwords, the UE_A10 may identify the corresponding type of congestionmanagement and the corresponding S-NSSAI and/or DNN as appliedcongestion management based on the 15th behavior. Besides, the UE_A10may store and manage one or more pieces of identification informationfrom the first identification information to the fourth identificationinformation and from the 11th identification information to the 18thidentification information in association with the applied congestionmanagement. Here, the 3rd identification information, and/or the 4thidentification information, and/or the 13th identification informationmay be stored and managed as information for identifying the appliedcongestion management.

A 16th behavior of the present embodiment is a behavior of the UEstopping the first timer in a case that a NW-initiated sessionmanagement procedure is performed with the first timer activated.

Here, for example, the 16th behavior may be a behavior of determining afirst timer to be stopped among a plurality of first timers activatedbased on 21st identification information and then stopping thedetermined timer in a case that the plurality of first timers areactivated. Additionally/alternatively, the 16th behavior may be abehavior of stopping a first timer associated with a congestionmanagement identified by a 17th behavior. It should be noted that whenthere are a plurality of congestion managements identified by the 17thbehavior, a timer associated with each congestion management may bestopped.

The 17th behavior of the present embodiment may be a behavior of the UEidentifying a congestion management whose application is to be stoppedamong one or more congestion managements applied by the UE based on thereception of a control message transmitted by the core network. Forexample, the UE may identify a congestion management whose applicationis to be stopped or changed based on the 21st identificationinformation.

Specifically, as described above, the UE may store the thirdidentification information and/or the fourth identification informationand/or the 13th identification information as information foridentifying a congestion management in the fourth process, and mayidentify the congestion management, in which the information foridentifying these congestion management matches the 13th identificationinformation included in the 21th identification information, as acongestion management whose application is to be stopped.

Additionally/alternatively, the UE may identify a congestion managementwhose application is to be stopped based on one piece or a combinationof multiple pieces of identification information from the 11thidentification information to the 18th identification informationincluded in the 21st identification information. Here, the details ofthe identification method may be the same as the identification processin the 15th behavior described in the fourth process in the example ofthe PDU session establishment procedure described below. In other words,the UE may identify the congestion management to be stopped by using amethod that is the same as the method for identifying the appliedcongestion management.

It should be noted that the UE may identify a plurality of congestionmanagements whose application is to be stopped. Hereinafter, thecongestion management identified by the method described above isconsidered to be a first congestion management, and a method foridentifying a second congestion management that is different from thefirst congestion management will be described.

For example, the UE may identify a congestion management associated witha DNN, which is the same as the DNN associated with the first congestionmanagement, as the second congestion management.Additionally/alternatively, the UE may identify a congestion managementassociated with S-NSSAI, which is the same as the S-NSSAI associatedwith the first congestion management, as the second congestionmanagement. It should be noted that identifying a plurality ofcongestion managements whose application is to be stopped may beconfigured to be performed only in a case that the first congestionmanagement and/or the second congestion management is a specific type ofcongestion management.

Specifically, the UE may identify the second congestion management whenthe first congestion management is any of the first congestionmanagement to the fourth congestion management.Additionally/alternatively, in specifying the second congestionmanagement, the UE may identify the second congestion management when acongestion management to be searched is any of the first congestionmanagement to the fourth congestion management. It should be noted thatin which type the first congestion management and/or the secondidentification information can identify a plurality of congestionmanagements may be preconfigured in a core network and/or a UE. Besides,the number of specific types of congestion managements allowed foridentification is not necessarily configured as one but may beconfigured as multiple.

The first identification information of the present embodiment isinformation for identifying a session belonging to a first NW slice. Inother words, the first identification information may be informationindicating that the UE expects to establish a PDU session belonging tothe first NW slice. Specifically, for example, the first identificationinformation can be information for identifying the first NW slice. Itshould be noted that the slice information may be identificationinformation indicating a specific S-NSSAI. In addition, the firstidentification information may be information for identifying a specificNW slice in the operator A network, or may be information for commonlyidentifying the same NW slice in the operator B (an operator other thanthe operator A). Further, the first identification information may beinformation for identifying the first NW slice configured by an HPLMN,may be information for identifying the first NW slice obtained from theAMF in a registration procedure, or may be information for identifyingthe first NW slice granted by a network. In addition, the firstidentification information may be information for identifying the firstNW slice stored for each PLMN.

The second identification information of the present embodiment may be aDNN (Data Network Name) and information used for identifying a DN (DataNetwork).

The third identification information of the present embodiment may be aPDU session ID and information used for identifying a PDU session.

The fourth identification information of the present embodiment may be aPTI (Procedure transaction identity), which is information foridentifying transmission and/or reception of a series of messages of aspecific session management procedure as one group, and may also beinformation used for identifying and/or distinguishing transmissionand/or reception of another series of session management-relatedmessages.

The 11th identification information of the present embodiment may beinformation indicating rejection of a PDU session establishment requestor a PDU session modification request. It should be noted that the PDUsession establishment request or the PDU session modification request isa request performed by the UE, and may include a DNN and/or S-NSSAI. Inother words, the 11th identification information may be informationindicating that the NW rejects the establishment request or themodification request for the PDU session corresponding to the DNN and/orS-NSSA.

In addition, the 11th identification information may be informationindicating re-attempt information.

In addition, the NW may transmit at least one identification informationof 12th identification information to 18th identification informationalong with the 11th identification information to the UE so as toindicate a congestion management to the UE. In other words, the NW maynotify the UE of a congestion management corresponding to one piece or acombination of multiple pieces of identification information from the12th identification information to the 18th identification information.On the other hand, the UE may identify a congestion managementcorresponding to one piece or a combination of multiple pieces ofidentification information from the 12th identification information tothe 18th identification information, and may perform processing based onthe identified congestion management. Specifically, the UE may startcounting the first timer associated with the identified congestionmanagement. Further, a timer value of the first timer may be determinedby using 14th identification information, a timer value configured inanother method such as using a value stored by the UE in advance may beconfigured, or a random value may be configured.

The 12th identification information of the present embodiment may be aDNN, which may be a DNN that is not allowed by the network, or may beinformation indicating that a DNN identified with the secondidentification information is not allowed. Further, the 12thidentification information may be the same DNN as that of the secondidentification information.

The 13th identification information of the present embodiment may be aPDU session ID and/or PTI that is a PDU session ID and/or PTI notallowed by the network, or may be information indicating that a PDUsession ID and/or PTI identified by the third identification informationis not allowed. Furthermore, the PDU Session ID of the 13thidentification information may be the same PDU session ID as that of thethird identification information. In addition, the PTI of the 13thidentification information may be the same PTI as that of the fourthidentification information.

Here, the 13th identification information may be used as information foridentifying congestion management of which the NW notifies the UE basedon the rejection of the PDU session establishment. In other words, theUE may store and manage the 13th identification information inassociation with a congestion management performed based on the 15thbehavior and use the 13th identification information as information foridentifying the performed congestion management. Besides, theinformation for identifying the congestion management may be constitutedby a combination of one or more pieces of identification informationfrom the 14th to the 18th identification information in addition to the13th identification information.

The 14th identification information of the present embodiment may beinformation indicating a value of a back-off timer. In other words, theback-off timer may be a value indicating a valid period of thecongestion management of which the NW notifies the UE based on therejection of the PDU session establishment. In other words, the UE mayuse the 14th identification information as a timer value in the 15thbehavior performed with the reception of the 14th identificationinformation. Further, the 14th identification information may includeinformation for identifying a type of congestion management in additionto the timer value. Specifically, the 14th identification informationmay include information for identifying which of the congestionmanagements from the first congestion management to the fourthcongestion management is applied. For example, the information foridentifying the type of the congestion management may be a timer namethat identifies each congestion management or may be a flag thatidentifies each congestion management. However, the present embodimentis not limited to the example described above, and the congestionmanagement may be identified by using other means, such as by using alocation stored in a control message and the like.

The 15th identification information of the present embodiment isinformation that indicates one or more cause values indicating a causefor which the present procedure is rejected. In other words, a causevalue may be information indicating a congestion management applied bythe NW to the present procedure, or may be information indicating acause value for rejecting the present procedure applied by the NW otherthan a congestion management.

It should be noted that a cause value may be information foridentifying, based on the rejection of the PDU session establishment,which of a congestion management among the congestion managements fromthe first congestion management to the fourth congestion management isindicated by the congestion management of which the NW notifies the UE.In this case, the NW may transmit a different value to the UE as a causevalue according to each congestion management from the first congestionmanagement to the fourth congestion management. The UE may interpreteach value transmitted as a cause value in advance, and identify, in the15th behavior based on at least the 15th identification information, acongestion management among the congestion managements from the firstcongestion management to the fourth congestion management.

Alternatively, the cause value may be information for identifying, basedon the rejection of the PDU session establishment, whether thecongestion management of which the NW notifies the UE is the firstcongestion management or any congestion management of the secondcongestion management, the third congestion management and the fourthcongestion management. In this case, the NW may transmit a differentvalue to the UE as a cause value depending on whether the congestionmanagement is the first congestion management or any congestionmanagement of the second congestion management, the third congestionmanagement and the fourth congestion management. The UE may interpreteach value transmitted as a cause value in advance, and identify, in the15th behavior based on at least the 15th identification information,whether the congestion management is the first congestion management orany of the second congestion management, the third congestion managementand the fourth congestion management.

Alternatively, the cause value may be information for identifying, basedon the rejection of the PDU session establishment, whether thecongestion management of which the NW notifies the UE is the firstcongestion management, the second congestion management, or anycongestion management of the third congestion management and the fourthcongestion management. In this case, the NW may transmit a differentvalue to the UE as a cause value depending on whether the congestionmanagement is the first congestion management, the second congestionmanagement, or any congestion management of the third congestionmanagement and the fourth congestion management. The UE may interpreteach value transmitted as a cause value in advance, and identify, in the15th behavior based on at least the 15th identification information,whether the congestion management is the first congestion management,the second congestion management, or any of the third congestionmanagement and the fourth congestion management.

Alternatively, the cause value may be information for identifying, basedon the rejection of the PDU session establishment, whether thecongestion management of which the NW notifies the UE is the firstcongestion management or the second congestion management, or the thirdcongestion management or the fourth congestion management. In this case,the NW may transmit a different value to the UE as a cause valuedepending on whether the congestion management is the first congestionmanagement or the second congestion management, or the third congestionmanagement or the fourth congestion management. Further, the UEinterprets each value transmitted as a cause value in advance, andidentifies, in the 15th behavior based on at least the 15thidentification information, whether the congestion management is thefirst congestion management or the second congestion management, or thethird congestion management or the fourth congestion management.

Alternatively, the cause value may be information for identifying, basedon the rejection of the PDU session establishment, whether thecongestion management of which the NW notifies the UE is the secondcongestion management or the third congestion management, or the firstcongestion management or the fourth congestion management. In this case,the NW may transmit a different value to the UE as a cause valuedepending on whether the congestion management is the second congestionmanagement or the third congestion management, or the first congestionmanagement or the fourth congestion management. Further, the UEinterprets each value transmitted as a cause value in advance, andidentifies, in the 15th behavior based on at least the 15thidentification information, whether the congestion management is thesecond congestion management or the third congestion management, or thefirst congestion management or the fourth congestion management.

Alternatively, the cause value may be information for identifying, basedon the rejection of the PDU session establishment, whether thecongestion management of which the NW notifies the UE is the secondcongestion management or the fourth congestion management, or the firstcongestion management or the third congestion management. In this case,the NW may transmit a different value to the UE as a cause valuedepending on whether the congestion management is the second congestionmanagement or the fourth congestion management, or the first congestionmanagement or the third congestion management. Further, the UEinterprets each value transmitted as a cause value in advance, andidentifies, in the 15th behavior based on at least the 15thidentification information, whether the congestion management is thesecond congestion management or the fourth congestion management, or thefirst congestion management or the third congestion management.

Alternatively, the cause value may be information indicating that the NWperforms a congestion management for the UE based on the rejection ofthe PDU session establishment. In other words, the cause value may beinformation for causing the UE to perform any of the first congestionmanagement to the fourth congestion management. In this case, the causevalue does not have to be information that can identify a particularcongestion management.

Further, a more detailed example of the cause value for rejecting thepresent procedure applied by the NW other than the congestion managementdescribed above may be a cause value (Missing or unknown DNN) that isnotified to the UE by the NW and indicates that an external DN rejectsthe present procedure because the present procedure does not include DNNinformation or includes an unknown DNN. Furthermore, a more detailedexample of the cause value may be a cause value (Unknown PDU sessiontype) that is notified to the UE by the NW and indicates that anexternal DN rejects the present procedure because the present procedurecannot recognize or does not allow the PDU session type of the presentprocedure. In addition, a more detailed example of the cause value maybe a cause value (User authentication or authorization failed) that isnotified to the UE by the NW and indicates that an external DN rejectsthe present procedure because of the failure of the user authenticationand authorization in the present procedure, or the revocation of theauthentication and authorization based on the external DN, or therevocation of the authentication and authorization based on the NW. Inaddition, a more detailed example of the cause value may be a causevalue (Request rejected, unspecified) for the NW to notify the UE that arequested service, operation, or resource reservation request isrejected based on an unspecified reason. In addition, a more detailedexample of the cause value may be a cause value (Service optiontemporarily out of order) for the NW to notify the UE that the NW istemporarily unable to receive a service request from the UE. Inaddition, a more detailed example of the cause value may be a causevalue (PTI already in use) for the NW to notify the UE that the PTIinserted by the UE is already in use. In addition, a more detailedexample of the cause value may be a cause value (Out of LADN servicearea) for the NW to notify the UE that the UE is out of the LADN servicearea. In addition, a more detailed example of the cause value may be acause value (PDU session type IPv4 allowed) for the NW to notify the UEthat only PDU session type IPv4 is allowed. In addition, a more detailedexample of the cause value may be a cause value (PDU session type IPv6only allowed) for the NW to notify the UE that only PDU session typeIPv6 is allowed. In addition, a more detailed example of the cause valuemay be a cause value (PDU session does not exist) for the NW to notifythe UE that the NW does not hold a targeted PDU session when the UEtransfers the PDU session from a non-3GPP access to a 3GPP access ortransfers the PDU session from an EPS to a 5GS. In addition, a moredetailed example of the cause value may be a cause value (Not supportedSSC mode) for the NW to notify the UE that the NW does not support theSSC mode requested by the UE. In addition, a more detailed example ofthe cause value may be a cause value (Missing or unknown DNN in a slice)that is notified to the UE by the NW and indicates that an external DNrejects the present procedure because the present procedure via aspecific slice does not include DNN information or includes an unknownDNN. In addition, a more detailed example of the cause value may be acause value (Maximum data rate per UE for user-plane integrityprotection is too low) that is notified to the UE by the NW andindicates that the UE does not meet the requirement of the maximum datatransmission rate for user-plane integrity protection required in aservice requested by the UE from the NW.

It should be noted that, in the present embodiment, when the thirdcongestion management is not performed, the implication corresponding tothe third congestion management is unnecessary in the cause value of the15th identification information described above, and the cause value ofthe 15th identification information may be a value from whichprocessing, description, and implication associated with the thirdcongestion management may be omitted from the above description. Inaddition, in the present embodiment, when the fourth congestionmanagement is not performed, the implication corresponding to the fourthcongestion management is unnecessary in the cause value of the 15thidentification information described above, and the cause value of the15th identification information may be a value from which processing,description, and implication associated with the fourth congestionmanagement may be omitted from the above description.

For a more detailed example, the 15th identification informationidentifying the first congestion management may be a cause valueindicating insufficient resources. In addition, the 15th identificationinformation identifying the second congestion management may be a causevalue indicating insufficient resources for a specific slice. Further,the 15th identification information identifying the third congestionmanagement may be a cause value indicating insufficient resources for aspecific slice and a DNN.

In this way, the 15th identification information may also be informationthat can identify the type of congestion management, and may beinformation indicating which type of congestion management correspondsto the back-off timer and/or the back-off timer value indicated by the14th identification information.

Therefore, the UE_A10 may also identify the type of congestionmanagement based on the 15th identification information. Further, basedon the 15th identification information, it may be determined which typeof congestion management corresponds to the back-off timer and/or theback-off timer value indicated by the 14th identification information.

The 16th identification information of the present embodiment is one ormore pieces of indication information indicating that the presentprocedure is rejected. In other words, the indication information may beinformation indicating a congestion management applied by the NW to thepresent procedure. The NW may indicate a congestion management appliedby the NW based on the 16th identification information.

For example, the indication information may be information indicatingwhich congestion management regulated by the NW to the UE in two or morecongestion managements among the congestion managements from the firstcongestion management to the fourth congestion management. Therefore,the NW may transmit a value associated with a regulated management to beapplied to the UE as indication information. Further, the UE mayinterpret each value transmitted as indication information in advance,and identify, in the 15th behavior based on at least the 16thidentification information, a congestion management among the congestionmanagements from the first congestion management to the fourthcongestion management. Here, the two or more congestion managementsamong the congestion managements from the first congestion management tothe fourth congestion management are congestion managements that can beidentified by using the indication information, and the congestionmanagements to be identified may be all four congestion managements, maybe the first congestion management and the second congestion management,may be the third congestion management and the fourth congestionmanagement, may be the second congestion management to the fourthcongestion management, or may be any other combination thereof.

It should be noted that the indication information does not necessarilyrequire values respectively corresponding to all of the congestionmanagements to be identified. For example, if the values of theindication information are respectively associated with and allocated tothe congestion managements excluding a congestion management A, then avalue of the indication information may not necessarily be configuredfor the congestion management A. In this case, the NW and the UE canidentify a congestion management as the first congestion management bynot transmitting and/or receiving the indication information. It shouldbe noted that the congestion management A may be any congestionmanagement among the first congestion management to the fourthcongestion management.

In addition, when the UE is notified of a congestion management based onthe transmission of a PDU session establishment reject message, theremay be cases that Identification may or may not be included depending onthe type of congestion management from the first congestion managementto the fourth congestion management. In other words, the NW may use theIdentification information as information indicating a congestionmanagement depending on the type of congestion management, or may useother identification information as information indicating a congestionmanagement depending on the type of congestion management without usingthe Identification information.

It should be noted that, in the present embodiment, when the thirdcongestion management is not performed, the implication corresponding tothe third congestion management is unnecessary in the indicationinformation of the 16th identification information described above, andthe indication information of the 16th identification information may beinformation from which processing, description, and implicationassociated with the third congestion management may be omitted from theabove description. In addition, in the present embodiment, when thefourth congestion management is not performed, the implicationcorresponding to the fourth congestion management is unnecessary in theindication information of the 16th identification information describedabove, and the indication information of the 16th identificationinformation may be information from which processing, description, andimplication associated with the fourth congestion management may beomitted from the above description.

The 17th identification information of the present embodiment is one ormore pieces of value information indicating that the present procedureis rejected. In other words, the value information may also beinformation indicating a congestion management applied by the NW to thepresent procedure. It should be noted that the 17th identificationinformation may be information including at least one piece ofidentification information for identifying one or more NW slicesincluded in the 18th identification information and/or the 12thidentification information.

The NW may indicate a congestion management applied by the NW based onthe 17th identification information. In other words, the NW may indicatewhich congestion management among the congestion managements from thefirst congestion management to the fourth congestion management isapplied based on the 17th identification information. Further, the NWmay indicate the DNN and/or the S-NSSAI that is subjected to congestionmanagement to be applied to the UE based on transmission of a PDUsession reject message based on the 17th identification information. Forexample, when the 17th identification information is just a DNN #1, itindicates that the first congestion management directed to the DNN #1 isapplied. When the 17th identification information is just S-NSSAI #1, itindicates that the second congestion management directed to the S-NSSAI#1 is applied. When the 17th information is configured with the DNN #1and S-NSSAI #1, it may indicate that the third congestion management orthe fourth congestion management directed to at least one of the DNN #1and/or the S-NSSAI #1 is applied.

It should be noted that the 17th identification information does notnecessarily have to be information that can identify which congestionmanagement among the congestion managements from the first congestionmanagement to the fourth congestion management is applied, and the 17thidentification information may be information indicating the DNN and/orthe S-NSSAI that is subjected to congestion management identified byother means, such as being identified based on other identificationinformation.

The 18th identification information of the present embodiment may beinformation indicating that a request for establishing a PDU sessionbelonging to a first NW slice is rejected, or may be informationindicating that a request for establishing a PDU session belonging tothe first NW slice or a request for modifying a PDU session (PDU sessionmodification) is not allowed. Here, the first NW slice may be an NWslice determined by the first identification information, or may be adifferent NW slice. Furthermore, the 18th identification information maybe information indicating that the establishment of a PDU sessionbelonging to a first NW slice is not allowed in a DN identified by the12th identification information, or may be information indicating thatthe establishment of a PDU session belonging to a first NW slice is notallowed in the PDU session identified by the 13th identificationinformation. Furthermore, the 11th identification information may beinformation indicating that the establishment of a PDU session belongingto a first slice is not allowed in a registration area and/or a trackingarea to which the UE_A10 currently belongs, or may be informationindicating that the establishment of a PDU session belonging to a firstNW slice is not allowed in an access network to which the UE_A10 isconnected. Further, the 11th identification information may beidentification information for determining an NW slice to which therejected PDU session request belongs or identifying one or more NWslices. Furthermore, the 18th identification information may beidentification information indicating assistance information for a radioaccess system to select an appropriate MME in a case that the UEswitches the connection destination to an EPS. It should be noted thatthe assistance information may be information indicating a DCN ID.Further, the 18th identification information may be a network sliceassociation rule that is a rule associating a plurality of pieces ofslice information.

The 21st identification information of the present embodiment may beinformation for stopping one or more first timers activated by the UE,or may be information indicating a first timer to be stopped among thefirst timers activated by the UE. Specifically, the 21st identificationinformation may be information indicating the 13th identificationinformation stored in the UE in association with the first timer.Furthermore, the 21st identification information may be informationindicating at least one piece of the 12th identification information tothe 18th identification information stored in the UE in association withthe first timer.

Furthermore, the 21st identification information may be information thatchanges the association of the first timer stored by the UE withinformation indicating at least one piece of the 13th identificationinformation to the 17th identification information. For example, when afirst timer for suppressing a UE-initiated session management of acombination of a DNN #A and an S-NSSAI #A is activated, the UE maychange the association target of the activated timer only to the S-NSSAI#A and recognize that a UE-initiated session management request to theDNN #A is allowed in a case that an NW-initiated session managementrequest including the 21st identification information that allows aconnection to the DNN #A is received. In other words, the 21stidentification information may be information indicating that thecongestion management applied at the time of reception of the 21stidentification information is changed to another congestion managementamong the congestion managements from the first to the fourth congestionmanagement.

Next, an initial procedure according to the present embodiment will bedescribed with reference to FIG. 9. Hereinafter, the initial procedurewill also be referred to as the present procedure, and the presentprocedure includes a Registration procedure, a UE-initiated PDU sessionestablishment procedure, and a network-initiated session managementprocedure. Details of the registration procedure, the UE-initiated PDUsession establishment procedure, and the network-initiated sessionmanagement procedure will be described below.

Specifically, each apparatus performs the registration procedure (S900),and the UE_A10 transitions to a state of being registered in the network(RM-REGISTERED state). Next, each apparatus performs the PDU sessionestablishment procedure (S902), and the UE_A10 establishes a PDU sessionwith the DN_A5 that provides a PDU connection service via the corenetwork_B190, and each apparatus transitions to a first state (S904). Itshould be noted that although this PDU session is assumed to beestablished via the access network and the UPF_A235, the procedure isnot limited thereto. That is, a UPF (UPF_C239) that is different fromthe UPF_A235 may be present between the UPF_A235 and the access network.At this time, the PDU session is established via the access network, theUPF_C239, and the UPF_A235. Next, each apparatus in the first state mayperform the network-initiated session management procedure at any timing(S906).

It should be noted that each apparatus may exchange various kinds ofcapability information and/or various kinds of request information ofeach apparatus in the registration procedure and/or the PDU sessionestablishment procedure and/or the network-initiated session managementprocedure. In addition, when each apparatus performs the exchange ofvarious kinds of information and/or negotiation of various requests inthe registration procedure, each apparatus may or may not perform theexchange of various kinds of information and/or the negotiation ofvarious requests in the PDU session establishment procedure and/or thenetwork-initiated session management procedure. In addition, when eachapparatus does not perform the exchange of various kinds of informationand/or the negotiation of various requests in the registrationprocedure, each apparatus may perform the exchange of various kinds ofinformation and/or the negotiation of various requests in the PDUsession establishment procedure and/or the network-initiated sessionmanagement procedure. In addition, even when each apparatus performs theexchange of various kinds of information and/or the negotiation ofvarious requests in the registration procedure, each apparatus mayperform the exchange of various kinds of information and/or thenegotiation of various requests in the PDU session establishmentprocedure and/or the network-initiated session management procedure.

In addition, each apparatus may perform the PDU session establishmentprocedure in the registration procedure or after the registrationprocedure is completed. Furthermore, when the PDU session establishmentprocedure is performed in the registration procedure, a PDU sessionestablishment request message may be included in a registration requestmessage and transmitted and/or received, and a PDU session establishmentaccept message may be included in a registration accept message andtransmitted and/or received, a PDU session establishment completemessage may be included in a registration complete message andtransmitted and/or received, and a PDU session establishment rejectmessage may be included in a registration reject message and transmittedand/or received. In addition, when the PDU session establishmentprocedure is performed in the registration procedure, each apparatus mayestablish a PDU session based on the completion of the registrationprocedure or may transition to a state in which a PDU session isestablished among the apparatuses.

In addition, each apparatus involved in the present procedure maytransmit and/or receive each control message described in the presentprocedure so as to transmit and/or receive one or more pieces ofidentification information included in each control message, and storeeach piece of identification information transmitted and/or received asa context.

[1.3.1. Overview of Registration Procedure]

First, an overview of the registration procedure will be described. Theregistration procedure is a procedure initiated by the UE_A10 to performregistration in a network (the access network and/or the corenetwork_B190 and/or the DN_A5). In a state in which the UE_A10 is notregistered in the network, the UE_A10 can perform the present procedureat any timing, for example, when power is turned on. In other words, ifthe UE_A10 is in a deregistered state (RM-DEREGISTERED state), the UEcan initiate the present procedure at any timing. In addition, eachapparatus may transition to a registered state (RM-REGISTERED state)based on the completion of the registration procedure.

Furthermore, the present procedure may be a procedure for updatinglocation registration information of the UE_A10 in the network, and/orfor regularly notifying the network of a state of the UE_A10 from theUE_A10, and/or for updating specific parameters related to the UE_A10 inthe network.

The UE_A10 may initiate the present procedure at the time when theUE_A10 performs mobility across TAs. In other words, the UE_A10 mayinitiate the present procedure at the time when the UE_A10 moves to a TAdifferent from the TA indicated on a TA list held by the UE_A10.Further, the UE_A10 may initiate the present procedure at the time whena running timer expires. Furthermore, the UE_A10 may initiate thepresent procedure at the time when a context of each apparatus needs tobe updated due to disconnection or invalidation (also referred to asdeactivation) of a PDU session. Furthermore, the UE_A10 may initiate thepresent procedure at the time when a change occurs in capabilityinformation and/or preference pertaining to PDU session establishment ofthe UE_A10. Furthermore, the UE_A10 may initiate the present procedureregularly. It should be noted that the UE_A10 is not limited to theabove and can perform the present procedure at any timing as long as aPDU session is established.

[1.3.1.1. Example of Registration Procedure]

An example procedure to perform the registration procedure will bedescribed with reference to FIG. 10. In the present section, the presentprocedure refers to the registration procedure. Each step of the presentprocedure will be described below.

First, the UE_A10 transmits a Registration Request message to theAMF_A240 via a NR node_A122 (also referred to as a gNB) and/or ng-eNB(S1000) (S1002) (S1004) to initiate the registration procedure. Inaddition, the UE_A10 may transmit an SM (Session Management) message(e.g., a PDU session establishment request message) included in aregistration request message or transmit the SM message (e.g., the PDUsession establishment request message) along with the registrationrequest message, so as to initiate a procedure for session management(SM), such as a PDU session establishment procedure, during theregistration procedure.

Specifically, the UE_A10 transmits an RRC (Radio Resource Control)message including the registration request message to the NR node_A122and/or ng-eNB (S1000). If the RRC message including the registrationrequest message is received, the NR node_A122 and/or ng-eNB retrievesthe registration request message from the RRC message and selects theAMF_A240 as a NF or a common CP function to which the registrationrequest message is routed (S1002). Here, the NR node_A122 and/or ng-eNBselects the AMF_A240 based on information included in the RRC message.The NR node_A122 and/or ng-eNB transmits or transfers the registrationrequest message to the selected AMF_A240 (S1004).

It should be noted that the registration request message is a NAS(Non-Access-Stratum) message transmitted and/or received on the N1interface. In addition, the RRC message is a control message transmittedand/or received between the UE_A10 and the NR node_A122 and/or ng-eNB.Further, the NAS message is processed in an NAS layer, the RRC messageis processed in an RRC layer, and the NAS layer is a layer higher thanthe RRC layer.

In addition, when there are a plurality of NSIs requesting registration,the UE_A10 may transmit a registration request message for each of theNSIs, or may transmit a plurality of registration request messagesincluded in one or more RRC messages. In addition, the above-describedplurality of registration request messages may be included in one ormore RRC messages and transmitted as one registration request message.

When a registration request message and/or a control message differentfrom the registration request message is received, the AMF_A240 performsfirst condition determination. The first condition determination is usedfor determining whether the AMF_A240 accepts a request of the UE_A10. Inthe first condition determination, the AMF_A240 determines whether thefirst condition determination is true or false. The AMF_A240 initiates aprocedure (A) in the present procedure when the first conditiondetermination is true (that is, the network accepts the request of theUE_A10), and initiates a procedure (B) in the present procedure when thefirst condition determination is false (that is, the network does notaccept the request of the UE_A10).

Next, steps performed when the first condition determination is true,that is, each step of the procedure (A) in the present procedure, willbe described. The AMF_A240 performs fourth condition determination, andinitiates the procedure (A) in the present procedure. The fourthcondition determination is to determine whether the AMF_A240 transmitsand/or receives an SM message to/from the SMF_A230. In other words, thefourth condition determination may determine whether the AMF_A240performs a PDU session establishment procedure in the present procedure.When the fourth condition determination is true (that is, the AMF_A240transmits and/or receives an SM message to and/or from the SMF_A230),the AMF_A240 selects the SMF_A230 and transmits and/or receives the SMmessage to and/or from the selected SMF_A230, and when the fourthcondition determination is false (that is, the AMF_A240 does nottransmit and/or receive an SM message to and/or from the SMF_A230), theAMF_A240 skips the process (S1006). It should be noted that when theAMF_A240 receives an SM message indicating a rejection from theSMF_A230, the AMF_A240 may stop the procedure (A) in the presentprocedure and initiate a procedure (B) in the present procedure.

In addition, the AMF_A240 transmits a Registration Accept message to theUE_A10 via the NR node_A122 based on the reception of the registrationrequest message from the UE_A10 and/or the completion of thetransmission and/or reception of the SM message to and/or from theSMF_A230 (S1008). For example, when the fourth condition determinationis true, the AMF_A240 may transmit the registration accept message basedon the reception of the registration request message from the UE_A10. Inaddition, when the fourth condition determination is false, the AMF_A240may transmit the registration accept message based on the completion ofthe transmission and/or reception of the SM message to and/or from theSMF_A230. Here, the registration accept message may be transmitted as aresponse message to the registration request message. In addition, theregistration accept message is a NAS message transmitted and/or receivedon the N1 interface, and for example, the AMF_A240 may transmit it as acontrol message of the N2 interface to the NR node_A122, and the NRnode_A122 that receives the message may include the message in an RRCmessage and transmit it to the UE_A10.

Further, when the fourth condition determination is true, the AMF_A240may include an SM message (e.g., a PDU session establishment acceptmessage) in the registration accept message and transmit it, or maytransmit the SM message (e.g., a PDU session establishment acceptmessage) along with the registration accept message. In addition, thistransmission method may be performed when the registration requestmessage includes an SM message (e.g., the PDU session establishmentrequest message) and the fourth condition determination is true. Inaddition, the transmission method may be performed when an SM message(e.g., the PDU session establishment request message) is included alongwith the registration request message and the fourth conditiondetermination is true. The AMF_A240 may indicate that the procedure forSM has been accepted by performing such a transmission method.

The UE_A10 receives the registration accept message via the NR node_A122(S1008). The UE_A10 receives the registration accept message torecognize the content of various kinds of identification informationincluded in the registration accept message.

Next, the UE_A10 transmits a Registration Complete message to theAMF_A240 based on the reception of the registration accept message(S1010). It should be noted that when the UE_A10 receives an SM messagesuch as a PDU session establishment accept message, the UE_A10 maytransmit an SM message such as a PDU session establishment completemessage included in the registration complete message, or may includethe SM message therein to indicate that the procedure for the SM iscompleted. Here, the registration complete message may be transmitted asa response message to the registration accept message. In addition, theregistration complete message is a NAS message transmitted and/orreceived on the N1 interface, and for example, the UE_A10 may include itin an RRC message and transmit it to the NR node_A122, and the NRnode_A122 that receives the message may transmit the message to theAMF_A240 as a control message of the N2 interface.

The AMF_A240 receives the registration complete message (S1010). Inaddition, each apparatus completes the procedure (A) in the presentprocedure based on the transmission and/or reception of the registrationaccept message and/or the registration complete message.

Next, steps performed when the first condition determination is false,that is, each step of the procedure (B) in the present procedure, willbe described. The AMF_A240 transmits a Registration Reject message tothe UE_A10 via the NR node_A122 (S1012) to initiate the procedure (B) inthe present procedure. Here, the registration reject message may betransmitted as a response message to the registration request message.In addition, the registration reject message is a NAS messagetransmitted and/or received on the N1 interface, and for example, theAMF_A240 may transmit it as a control message of the N2 interface to theNR node_A122, and the NR node_A122 that receives the message may includethe message in an RRC message and transmit it to the UE_A10. Further,the registration reject message transmitted by the AMF_A240 is notlimited thereto as long as it is a message for rejecting the request ofthe UE_A10.

It should be noted that the procedure (B) of the present procedure maybe sometimes initiated when the procedure (A) of the procedure isterminated. In the procedure (A), when the fourth conditiondetermination is true, the AMF_A240 may include an SM message indicatingrejection, such as a PDU session establishment reject message or thelike, in the registration reject message and transmit the SM message, orindicate that a procedure for the SM is rejected by including the SMmessage indicating rejection. In that case, the UE_A10 may furtherreceive the SM message indicating rejection such as the PDU sessionestablishment reject message, or may recognize that the procedure for SMis rejected.

Furthermore, the UE_A10 may receive a registration reject message or maynot receive a registration accept message to recognize that a request ofthe UE_A10 is rejected. Each apparatus completes the procedure (B) inthe present procedure based on the transmission and/or reception of theregistration reject message.

Each apparatus completes the present procedure (registration procedure)based on the completion of the procedure (A) or (B) of the presentprocedure. It should be noted that each apparatus may transition to astate in which the UE_A10 is registered in the network (RM_REGISTEREDstate) based on the completion of the procedure (A) of the presentprocedure, or may maintain a state in which the UE_A10 is not registeredin the network (RM_DEREGISTERED state) based on the completion of theprocedure (B) of the present procedure. In addition, a transition toeach state of each apparatus may be performed based on completion of thepresent procedure, or may be performed based on establishment of a PDUsession.

Further, each apparatus may, based on the completion of the presentprocedure, perform processing based on identification informationtransmitted and/or received in the present procedure.

In addition, the first condition determination may be performed based onidentification information, and/or subscriber information and/or anoperator policy included in the registration request message. Forexample, the first condition determination may be true when the networkallows a request of the UE_A10. In addition, the first conditiondetermination may be false when the network does not allow a request ofthe UE_A10. Furthermore, the first condition determination may be truewhen a network, to which the UE_A10 is to be registered, and/or anapparatus in the network supports a function requested by the UE_A10,and may be false when the network and/or the apparatus does not supportthe function. Further, the first condition determination may be truewhen it is determined that the network is congested, and may be falsewhen it is determined that the network is not congested. It should benoted that conditions for determining whether the first conditiondetermination is true or false may not be limited to the aboveconditions.

In addition, the fourth condition determination may also be performedbased on whether the AMF_A240 receives an SM or may be performed basedon whether an SM message is included in the registration requestmessage. For example, the fourth condition determination may be truewhen the AMF_A240 receives the SM and/or the SM message is included inthe registration request message, and may be false when the AMF_A240does not receive the SM and/or the SM message is not included in theregistration request message. It should be noted that conditions fordetermining whether the fourth condition determination is true or falsemay not be limited to the above conditions.

[1.3.2. Overview of PDU Session Establishment Procedure]

Next, an overview of the PDU session establishment procedure performedto establish a PDU session with the DN_A5 will be described.Hereinafter, the PDU session establishment procedure will also bereferred to as the present procedure. The present procedure is aprocedure for each apparatus to establish a PDU session. It should benoted that each apparatus may perform the present procedure in a statein which the registration procedure is completed or during theregistration procedure. In addition, each apparatus may initiate thepresent procedure in a registered state, or may initiate the presentprocedure at any timing after the registration procedure. In addition,each apparatus may establish a PDU session based on the completion of aPDU session establishment procedure. Further, each apparatus may performthe present procedure multiple times to establish a plurality of PDUsessions.

[1.3.2.1. Example of PDU Session Establishment Procedure]

An example procedure to perform the PDU session establishment procedurewill be described with reference to FIG. 11. Each step of the presentprocedure will be described below. First, the UE_A10 transmits a PDUSession Establishment Request message to a core network_B via an accessnetwork_B (S1100), and initiates the PDU session establishmentprocedure.

Specifically, the UE_A10 transmits the PDU session establishment requestmessage to the AMF_A240 in the core network_B190 via the NR node_A122 byusing the N1 interface (S1100). The AMF_A receives the PDU sessionestablishment request message and performs third conditiondetermination. The third condition determination is used for determiningwhether the AMF_A accepts the request of the UE_A10. In the thirdcondition determination, the AMF_A determines whether the fifthcondition determination is true or false. When the third conditiondetermination is true, the core network_B initiates a process #1 (S1101)in the core network, and when the third condition determination isfalse, the core network_B initiates the procedure (B) in the presentprocedure. It should be noted that steps performed when the thirdcondition determination is false will be described below. Here, theprocess #1 in the core network may be selection of an SMF by the AMF_Ain the core network_B190 and/or transmission and/or reception of the PDUsession establishment request message between the AMF_A and the SMF_A.

The core network_B190 initiates the process #1 in the core network. Inthe process #1 of the core network, the AMF_A240 may select the SMF_A230as an NF as a routing destination of the PDU session establishmentrequest message, and may transmit or transfer the PDU sessionestablishment request message to the selected SMF_A230 by using an N11interface. Here, the AMF_A240 may select the SMF_A230 as a routingdestination based on information included in the PDU sessionestablishment request message. More specifically, the AMF_A240 mayselect the SMF_A230 as a routing destination based on each piece ofidentification information acquired based on the reception of the PDUsession establishment request message, and/or subscriber information,and/or network capability information, and/or an operator policy, and/ora network state, and/or a context already held by the AMF_A240.

It should be noted that the PDU session establishment request messagemay be a NAS message. In addition, the PDU session establishment requestmessage may only need to be a message requesting establishment of a PDUsession and is not limited to this.

Here, the UE_A10 may include one or more pieces of identificationinformation from the first identification information to the fourthidentification information in the PDU session establishment requestmessage, or may indicate a request of the UE_A10 by including thesepieces of identification information. It should be noted that two ormore pieces of identification information of the identificationinformation may be configured as one or more pieces of identificationinformation.

Further, the UE_A10 may include the first identification informationand/or the second identification information and/or the thirdidentification information and/or the fourth identification informationin the PDU session establishment request message and transmit them torequest for the establishment of a PDU session belonging to a networkslice, to indicate a network slice which the PDU session belongs to andis requested by the UE_A10, or to indicate a network slice to which thePDU session will belong.

More particularly, the UE_A10 may transmit the first identificationinformation and the second identification information in associationwith each other to request for the establishment of a PDU sessionbelonging to a network slice in a PDU session established for a DNidentified with the second identification information, to indicate anetwork slice which the PDU session belongs to and is requested by theUE_A10, or to indicate a network slice to which the PDU session willbelong.

Further, the UE_A10 may combine and transmit two or more pieces ofidentification information from the first identification information tothe fourth identification information to make a request combining theabove-described matters. It should be noted that matters indicated bythe UE_A10 transmitting each piece of identification information may notbe limited thereto.

It should be noted that the UE_A10 may determine which piece ofidentification information from the first identification information tothe fourth identification information is to be included in the PDUsession establishment request message based on capability information ofthe UE_A10, and/or a policy such as a UE policy, and/or a preference ofthe UE_A10, and/or an application (higher layer). It should be notedthat the determination performed by the UE_A10 as to which piece ofidentification information is to be included in the PDU sessionestablishment request message is not limited thereto.

The SMF_A230 in the core network_B190 receives the PDU sessionestablishment request message and performs the third conditiondetermination. The third condition determination is used for determiningwhether the SMF_A230 accepts the request of the UE_A10. In the thirdcondition determination, the SMF_A230 determines whether the thirdcondition determination is true or false. When the third conditiondetermination is true, the SMF_A230 initiates the procedure (A) of thepresent procedure, and when the third condition determination is false,the SMF_A230 initiates the procedure (B) of the present procedure. Itshould be noted that steps performed when the third conditiondetermination is false will be described below.

Next, steps performed when the third condition determination is true,that is, each step of the procedure (A) in the present procedure, willbe described. The SMF_A230 selects the UPF_A235 with which the PDUsession is to be established and performs 11th condition determination.

Here, the 11th condition determination is used for determining whethereach apparatus performs a process #2 in the core network. Here, theprocess #2 in the core network may include initiation and/or executionof a PDU session establishment authentication procedure performed byeach apparatus and/or transmission and/or reception of a SessionEstablishment request message between the SMF_A and UPF_A in the corenetwork_B190, and/or transmission and/or reception of a SessionEstablishment response message, and the like (S1103). In the 11thcondition determination, the SMF_A230 determines whether the 11thcondition determination is true or false. The SMF_A230 initiates a PDUsession establishment authentication and/or authorization procedure withthe 11th condition determination is true, and omits the PDU sessionestablishment authentication and/or authorization procedure when the11th condition determination is false. It should be noted that thedetails of the PDU session establishment authentication and/orauthorization procedure of the process #2 in the core network will bedescribed below.

Next, the SMF_A230 transmits a session establishment request message tothe selected UPF_A235 based on the 11th condition determination and/orcompletion of the PDU session establishment authentication and/orauthorization procedure, and initiates the procedure (A) of the presentprocedure. It should be noted that the SMF_A230 may initiate theprocedure (B) of the present procedure without initiating the procedure(A) of the present procedure based on the completion of the PDU sessionestablishment authentication and/or authorization procedure.

Here, the SMF_A230 may select one or more UPFs_A235 based on each pieceof identification information acquired based on the reception of the PDUsession establishment request message, and/or network capabilityinformation, and/or subscriber information, and/or an operator policy,and/or a network state, and/or a context already held by the SMF_A230.It should be noted that when a plurality of UPFs_A235 are selected, theSMF_A230 may transmit the session establishment request message to eachUPF_A235.

The UPF_A235 receives the session establishment request message andgenerates a context for the PDU session. In addition, the UPF_A235transmits a session establishment response message to the SMF_A230 basedon the reception of the session establishment request message and/or thecreation of the context for the PDU session. Further, the SMF_A230receives the session establishment response message. It should be notedthat the session establishment request message and the sessionestablishment response message may be control messages transmittedand/or received on the N4 interface. Further, the session establishmentresponse message may be a response message to the session establishmentrequest message.

Further, the SMF_A230 may perform address assignment to assign anaddress to the UE_A10 based on the reception of the PDU sessionestablishment request message and/or the selection of the UPF_A235and/or the reception of the session establishment response message. Itshould be noted that the SMF_A230 may perform the address assignment toassign the address to the UE_A10 during the PDU session establishmentprocedure, or may perform the address assignment to assign the addressto the UE_A10 after the completion of the PDU session establishmentprocedure.

Specifically, when the SMF_A230 assigns an IPv4 address without usingDHCPv4, the SMF_A230 may perform the address assignment during the PDUsession establishment procedure or may transmit the assigned address tothe UE_A10. In addition, when the SMF_A230 assigns the IPv4 address,and/or the IPv6 address, and/or the IPv6 prefix by using DHCPv4 orDHCPv6 or SLAAC (Stateless Address Autoconfiguration), the SMF_A230 mayperform the address assignment after the PDU session establishmentprocedure or may transmit the assigned address to the UE_A10. It shouldbe noted that the address assignment performed by SMF_A230 is notlimited thereto.

Further, the SMF_A230 may include the assigned address in the PDUsession establishment accept message and may transmit it to the UE_A10based on the completion of the address assignment for the address to beassigned to the UE_A10, or may transmit the assigned address to theUE_A10 after the completion of the PDU session establishment procedure.

The SMF_A230 transmits the PDU session establishment accept message tothe UE_A10 via the AMF_A240 based on the reception of the PDU sessionestablishment request message, and/or the selection of the UPF_A235,and/or the reception of the session establishment response message,and/or the completion of the address assignment for the address to beassigned to the UE_A10 (S1110).

Specifically, the SMF_A230 transmits the PDU session establishmentaccept message to the AMF_A240 by using the N11 interface, and theAMF_A240 that receives the PDU session establishment accept messagetransmits the PDU session establishment accept message to the UE_A10 byusing the N1 interface.

It should be noted that when the PDU session is a PDN connection, thePDU session establishment accept message may be a PDN connectivityaccept message. Further, the PDU session establishment accept messagemay be a NAS message transmitted and/or received on the N11 interfaceand the N1 interface. In addition, the PDU session establishment acceptmessage is not limited to the above and may be any message indicatingthat the establishment of a PDU session is accepted.

The UE_A10 receives the PDU session establishment accept message fromthe SMF_A230. The UE_A10 receives the PDU session establishment acceptmessage to recognize the content of various kinds of identificationinformation included in the PDU session establishment accept message.

Next, the UE_A10 transmits a PDU session establishment complete messageto the SMF_A230 via the AMF_A240 based on the completion of thereception of the PDU session establishment accept message (S1114).Furthermore, the SMF_A230 receives the PDU session establishmentcomplete message and performs the second condition determination.

Specifically, the UE_A10 transmits the PDU session establishmentcomplete message to the AMF_A240 by using the N1 interface, and theAMF_A240 that has received the PDU session establishment completemessage transmits the PDU session establishment complete message to theSMF_A230 by using the N11 interface.

It should be noted that when the PDU session is a PDN connection, thePDU session establishment complete message may be a PDN connectivitycomplete message or may be an activate default EPS bearer context acceptmessage. Furthermore, the PDU session establishment complete message maybe a NAS message transmitted and/or received on the N1 interface and theN11 interface. In addition, the PDU session establishment completemessage only needs to be a response message to the PDU sessionestablishment accept message, but the message is not limited to this,and may be a message indicating that the PDU session establishmentprocedure is completed.

The second condition determination is used for the SMF_A230 to determinea type of the message to be transmitted and/or received on the N4interface. When the second condition determination is true, a process #3in the core network may be initiated (S1115). Here, the process #3 inthe core network may include transmission and/or reception of a sessionmodification request message, and/or transmission and/or reception of asession modification response message, and the like. The SMF_A230transmits a session modification request message to the UPF_A235, andfurther receives a session modification accept message transmitted fromthe UPF_A235 that receives the session modification request message. Inaddition, when the second condition determination is false, the SMF_A230performs the process #2 in the core network. That is, the SMF_Atransmits a session establishment request message to the UPF_A235, andfurther receives the session modification accept message transmittedfrom the UPF_A235 that receives the session establishment requestmessage.

Each apparatus completes the procedure (A) in the present procedurebased on the transmission and/or reception of the PDU sessionestablishment complete message, and/or the transmission and/or receptionof the session modification response message, and/or the transmissionand/or reception of the session establishment response message, and/orthe transmission and/or reception of an RA (Router Advertisement).

Next, steps performed when the third condition determination is false,that is, each step of the procedure (B) in the present procedure, willbe described. The SMF_A230 transmits a PDU session establishment rejectmessage to the UE_A10 via the AMF_A240 (S1122) and initiates theprocedure (B) in the present procedure.

Specifically, the SMF_A230 transmits the PDU session establishmentreject message to the AMF_A240 by using the N11 interface, and theAMF_A240 that receives the PDU session establishment request messagetransmits the PDU session establishment reject message to the UE_A10 byusing the N1 interface.

It should be noted that when the PDU session is a PDN connection, thePDU session establishment reject message may be a PDN connectivityreject message. Further, the PDU session establishment reject messagemay be a NAS message transmitted and/or received on the N11 interfaceand the N1 interface. In addition, the PDU session establishment rejectmessage is not limited to the above and may be any message indicatingthat the establishment of the PDU session is rejected.

Here, the SMF_A230 may include one or more pieces of identificationinformation from the 11th identification information to the 18thidentification information in the PDU session establishment rejectmessage, or may indicate that a request of the UE_A10 is rejected byincluding these pieces of identification information. It should be notedthat two or more pieces of identification information of theidentification information may be configured as one or more pieces ofidentification information.

Furthermore, the SMF_A230 may include 11th identification informationand/or 12th identification information and/or 13th identificationinformation and/or 14th identification information and/or 15thidentification information and/or 16th identification information and/or17th identification information and/or 18th identification informationin the PDU session establishment reject message and transmit them toindicate that a request for establishing a PDU session belonging to anetwork slice is rejected, or to indicate a network slice that is notallowed to belong to the PDU session.

More particularly, the SMF_A230 may transmit the 18th identificationinformation and the 12th identification information in association witheach other to indicate that, in a PDU session established for the DNidentified with the 12th identification information, a request forestablishing a PDU session belonging to a network slice is rejected, orto indicate a network slice that is not allowed to belong to the PDUsession.

Furthermore, the SMF_A230 may include the 18th identificationinformation in the PDU session establishment reject message and transmitit to indicate that, in a registration area and/or a tracking area towhich the UE_A10 currently belongs, a request for establishing a PDUsession belonging to a network slice is rejected, or to indicate anetwork slice that is not allowed to belong to the PDU session.

Furthermore, the SMF_A230 may include the 18th identificationinformation in the PDU session establishment reject message and transmitit to indicate that, in an access network to which the UE_A10 iscurrently connected, a request for establishing a PDU session belongingto a network slice is rejected, or to indicate a network slice that isnot allowed to belong to the PDU session.

Furthermore, the SMF_A230 may include the 11th identificationinformation and/or the 14th identification information in the PDUsession establishment reject message and transmit them to indicate avalue of the first timer and to indicate whether a procedure that is thesame as the present procedure needs to be performed again after thecompletion of the present procedure.

Furthermore, the SMF_A230 may combine and transmit two or more pieces ofidentification information from the 11th identification information tothe 18th identification information to make a request combining theabove-described matters. It should be noted that matters indicated bythe SMF_A230 transmitting each piece of identification information maynot be limited thereto.

It should be noted that the SMF_A230 may determine which piece ofidentification information from the 11th identification information tothe 18th identification information is to be included in the PDU sessionestablishment reject message based on the received identificationinformation, and/or network capability information, and/or a policy suchas an operator policy, and/or a network state.

In addition, the 12th identification information may be informationindicating a DNN that is the same as the DNN indicated by the secondidentification information. Furthermore, the 13th identificationinformation may be information indicating a PDU session ID that is thesame as the PDU session ID indicated by the third identificationinformation. Further, the 18th identification information may beinformation transmitted when the first identification information isreceived and/or when the network slice indicated by the firstidentification information is not allowed by the network. It should benoted that the determination performed by the SMF_A230 as to which pieceof identification information is to be included in the PDU sessionestablishment reject message is not limited thereto.

As described above, the core network_B190 notifies the UE_A10 of acongestion management to be applied by transmitting a PDU session rejectmessage. As a result, the core network_B190 may notify the applicationof a congestion management to the UE_A10, and/or indication to theUE_A10 that the congestion management is to be performed, and/orinformation for identifying the type of congestion management to beapplied, and/or information for identifying a congestion managementtarget such as a DNN and/or S-NSSAI corresponding to the congestionmanagement to be applied, and/or a value of the timer associated withthe congestion management to be applied.

Here, each piece of the above-described information may be informationidentified by one or more pieces of identification information from the11th identification information to the 18th identification information.

The UE_A10 may include one or more pieces of identification informationfrom the 11th identification information to the 18th identificationinformation in the PDU session establishment reject message receivedfrom the SMF_A230.

Next, the UE_A10 performs a fourth process based on the reception of thePDU session establishment reject message (S1124). In addition, theUE_A10 may perform the fourth process based on the completion of thepresent procedure.

Hereinafter, a first example of the fourth process will be described.

Here, the fourth process may be a process in which the UE_A10 recognizesthe matter indicated by the SMF_A230. Furthermore, the fourth processmay be a process in which the UE_A10 stores the received identificationinformation as a context, or may be a process in which the UE transfersthe received identification information to a higher layer and/or a lowerlayer. Furthermore, the fourth process may be a process in which theUE_A10 recognizes that a request for the present procedure is rejected.

Furthermore, when the UE_A10 receives the 14th identificationinformation and the 11th identification information, the fourth processmay be a process in which the UE_A10 sets the value indicated by the14th identification information as the first timer value, or may be aprocess of starting the first timer with the set timer value.Furthermore, when the UE_A10 receives the 11th identificationinformation, the fourth process may be a process of performing one ormore behaviors among the first to the 11th behaviors.

Further, when the UE_A10 receives the 18th identification informationand the 11th identification information, the fourth process may be aprocess in which the UE_A10 performs the 12th behavior based oninformation for identifying an NW slice included in the 18thidentification information, and a network slice-associated rule includedin the 18th identification information or a network slice-associatedrule held and preconfigured in the UE_A10.

Furthermore, when the UE_A10 receives a plurality of pieces of the 14thidentification information and 11th identification information, thefourth process may be a process in which the UE_A10 performs the 13thbehavior based on a plurality of first timers included in each piece ofthe 14th identification information and a priority management rule ofthe back-off timer held by the UE_A10.

Furthermore, when the UE_A10 receives a plurality of pieces of the 14thidentification information and the 11th identification information, thefourth process may be a process in which the UE_A10 performs the 14thbehavior based on a plurality of first timers included in each piece ofthe 14th identification information.

Here, the 12th to the 15th behaviors may be congestion managementsinitiated and performed by the UE_A10 based on rules and/or policieswithin the UE_A10. Specifically, for example, the UE_A10 may beconfigured to include the following elements in a storage unit and/or acontroller within the UE_A10: a policy (UE policy) and/or a rule, amanagement function of the policy and/or the rule, a policy enforcerthat causes the UE_A10 to operate based on the policy and/or the rule,one or more applications, and a session management instances (sessionmanager) for managing one or more PDU sessions to be established orattempted to be established based on a request from each application,and may implement congestion management initiated by the UE_A10 byperforming any of the 12th to the 15th behaviors as the fourth processbased on the above elements. Here, the policy and/or the rule mayinclude one or more of a network slice-associated rule and/or a prioritymanagement rule of a back-off timer, and/or an NSSP (Network SliceSelection Policy), which may further be preconfigured in the UE_A10 orreceived from the network. In addition, here, the policy enforcer may bean NSSP enforcer. In addition, here, the application may be anapplication layer protocol, and a PDU session may be established orattempted to be established based on a request from the applicationlayer protocol. In addition, here, the session management instance maybe a software element dynamically generated on a per PDU session basis.In addition, here, the S-NSSAI may be grouped as internal processing ofthe UE_A10, or processing based on the grouping of the S-NSSAI may beperformed. It should be noted that an internal configuration andprocessing of the UE_A10 are not limited thereto, and each element maybe implemented by software or may be performed as software processingwithin the UE_A10.

Furthermore, the UE_A10 may switch to an EPS in the fourth process orbased on the completion of the fourth process, and may initiate positionregistration at the EPS based on the DCN ID included in the 18thidentification information. It should be noted that the switch of theUE_A10 to the EPS may be based on a handover procedure, or may be a RATswitch initiated by the UE_A10. In addition, when the UE_A10 receivesthe 18th identification information including the DCN ID, the UE_A10 mayperform the switch to the EPS during the fourth process or after thecompletion of the fourth process.

Furthermore, the fourth process may be a process in which the UE_A10initiates the present procedure again after a certain period of time, ormay be a process of transitioning to a state in which the request of theUE_A10 is limited or restricted.

Besides, the UE_A10 may transition to a first state according to thecompletion of the fourth process.

Next, a second example of the fourth process will be described.

Here, the fourth process may be a process in which the UE_A10 recognizesthe matter indicated by the SMF_A230. Furthermore, the fourth processmay also be a process in which the UE_A10 stores the receivedidentification information as a context, or may be a process in whichthe UE transfers the received identification information to a higherlayer and/or a lower layer.

Furthermore, in the fourth process, processing may be performed toidentify the application of a congestion management based on one or morepieces of identification information from the 11th identificationinformation to the 18th identification information.

Furthermore, in the fourth process, processing may be performed toidentify which type of congestion managements to be applied from thefirst congestion management to the fourth congestion management and toidentify the DNN and/or the S-NSSAI associated with the congestedmanagement to be applied based on one or more pieces of identificationinformation from the 11th identification information to the 18thidentification information. More specifically, the present process maybe the process described in the 15th behavior.

Furthermore, in the fourth process, based on one or more pieces ofidentification information from the 11th identification information tothe 18th identification information, a value configured to the firsttimer indicated by the 14th identification information associated with acongestion management to be applied may be identified and configured,and the counting of a first timer may be started. More specifically, thepresent process may be the process described in the 8th behavior.

Furthermore, in the fourth process, one or more of behaviors from firstbehavior to the seventh behavior may be performed in accordance with theinitiation or completion of any of the processes described above.

Furthermore, in the fourth process, one or more of behaviors from theninth behavior to the 15th behavior may be performed in accordance withthe initiation or completion of any of the processes described above.

Besides, the UE_A10 may transition to a first state according to thecompletion of the fourth process.

Although detailed processes for the fourth process have been describedby using the first example and the second example, the fourth processmay not be limited to these processes. For example, the fourth processmay be a combined process of a part of the plurality of detailedprocesses described in the first example and a part of the plurality ofdetailed processes described in the second example.

Furthermore, the UE_A10 may receive the PDU session establishment rejectmessage or may not receive the PDU session establishment accept messageto recognize that a request of the UE_A10 is rejected. Each apparatuscompletes the procedure (B) in the present procedure based on thetransmission and/or reception of the PDU session establishment rejectmessage.

Each apparatus completes the present procedure based on the completionof the procedure (A) or (B) of the present procedure. It should be notedthat each apparatus may transition to a state in which the PDU sessionis established based on the completion of the procedure (A) of thepresent procedure, or each apparatus may recognize that the presentprocedure is rejected, transition to a state in which the PDU session isnot established, or transition to the first state based on thecompletion of the procedure (B) or the present procedure.

Furthermore, each apparatus may, based on the completion of the presentprocedure, perform processing based on identification informationtransmitted and/or received in the present procedure. In other words,the UE_A10 may perform the fourth process based on the completion of thepresent procedure, or may transition to the first state after thecompletion of the fourth process.

In addition, the third condition determination may be performed based onthe identification information included in the PDU session establishmentrequest message, and/or subscriber information, and/or an operatorpolicy. For example, the third condition determination may be true whena network allows a request of the UE_A10. In addition, the thirdcondition determination may be false when a network does not allow arequest of the UE_A10. Furthermore, the third condition determinationmay be true when a network, to which the UE_A10 is to be connected,and/or an apparatus in the network supports a function requested by theUE_A10, and may be false when the network and/or the apparatus does notsupport the function. Further, the third condition determination may betrue when it is determined that the network is congested, and may befalse when it is determined that the network is not congested. It shouldbe noted that conditions for determining whether the third conditiondetermination is true or false may not be limited to the aboveconditions.

In addition, the second condition determination may be performed basedon whether a session on the N4 interface for the PDU session isestablished. For example, the second condition determination may be truewhen the session on the N4 interface for the PDU session is established,and may be false when the session on the N4 interface for the PDUsession is not established. It should be noted that conditions fordetermining whether the second condition determination is true or falsemay not be limited to the above conditions.

In addition, the 11th condition determination may be performed based onthe identification information included in the PDU session establishmentrequest message, and/or subscriber information, and/or an operatorpolicy. For example, the 11th condition determination may be true whenthe network allows authentication and/or authorization by the DN_A5 tobe performed during the present procedure. In addition, the 11thcondition determination may be false when the network does not allowauthentication and/or authorization by the DN_A5 to be performed duringthe present procedure. Furthermore, the 11th condition determination maybe true when a network serving as a connection destination of the UE_A10and/or an apparatus in the network support performing authenticationand/or authorization by the DN_A5 during the present procedure, or maybe false when the network and/or the apparatus do not support performingauthentication and/or authorization by the DN_A5 during the presentprocedure. Furthermore, the 11th condition determination may be truewhen 61st identification information is received, and may be false whenthe 61st identification information is not received. In other words, the11th condition determination may be true when a container includinginformation such as SM PDU DN Request Container and/or a plurality ofpieces of information is received, and may be false when the containeris not received. It should be noted that conditions for determiningwhether the 11th condition determination is true or false may not belimited to the above conditions.

The transmission and/or reception of the PDU session reject message inthe above-described procedure causes the core network_B190 to notify theUE_A10 of a congestion management to be applied, and the UE_A10 canapply the congestion management indicated by the core network_B190.Further, the core network_B190 and the UE_A10 may apply a plurality ofcongestion managements by performing the procedures and processesdescribed in the present procedure multiple times. It should be notedthat the applied congestion managements may be different types ofcongestion managements, and/or congestion managements corresponding todifferent DNNs, and/or congestion managements corresponding to differentS-NNSAIs, and/or congestion managements with different combinations ofDNNs and S-NSSAIs.

[1.3.3. Overview of Network-Initiated Session Management Procedure]

Next, an overview of a network-initiated session management procedurewill be described. Hereinafter, the network-initiated session managementprocedure will also be referred to as the present procedure. The presentprocedure is a procedure for a session management initiated andperformed by the network for an established PDU session. It should benoted that the present procedure may be performed at any timing afterthe registration procedure and/or the PDU session establishmentprocedure described above is completed and each apparatus transitions tothe first state. In addition, each apparatus may transmit and/or receivea message including identification information for stopping or modifyinga congestion management during the present procedure, or may initiate abehavior based on a new congestion management indicated by the networkbased on the completion of the present procedure.

Besides, the UE_A10 may stop the application of the congestionmanagement identified based on control information transmitted and/orreceived through the present procedure. In other words, the corenetwork_B190 may initiate the present procedure and transmit the controlmessage and the control information of the present procedure to theUE_A10 to notify the UE_A10 to stop the application of an identifiablecongestion management by using these control information.

It should be noted that the present procedure may be a network-initiatedPDU session modification procedure, and/or a network-initiated PDUsession release procedure, or the like, or may perform anetwork-initiated session management procedure that is not limited tothe above. It should be noted that each apparatus may transmit and/orreceive a PDU session modification message in the network-initiated PDUsession modification procedure, or may transmit and/or receive a PDUsession release message in the network-initiated PDU session releaseprocedure.

[1.3.3.1. Example of First Network-Initiated Session ManagementProcedure]

An example of a network-initiated session management procedure will bedescribed with reference to FIG. 12. In this section, the presentprocedure refers to the network-initiated session management procedure.Each step of the present procedure will be described below.

As described above, based on the completion of the registrationprocedure and/or the PDU session establishment procedure, each apparatusin the UE_A10 and core network_B190 that transitions to the first state(S1200) initiates the network-initiated session management procedure atany timing. Here, the apparatus in the core network_B190 that initiatesthe present procedure may be the SMF_A and/or the AMF_A, and the UE_Amay transmit and/or receive a message in the present procedure via theAMF_A and/or the access network_B.

Specifically, the apparatus in the core network_B190 transmits anetwork-initiated session management request message to the UE_A(S1202). Here, the apparatus in the core network_B190 may include the21st identification information in the network-initiated sessionmanagement request message, or may indicate a request of the corenetwork_B190 by including this identification information.

Next, the UE_A receiving the network-initiated session managementrequest message transmits a network-initiated session managementcomplete message (S1204). Furthermore, the UE_A may perform a fifthprocess based on the 21st identification information received from thecore network_B190 (S1206), and complete the present procedure. Inaddition, the UE_A10 may perform the fifth process based on thecompletion of the present procedure.

An example of a fifth process will be described below.

Here, the fifth process may be a process in which the UE_A10 recognizesthe matter indicated by the core network_B190, or may be a process inwhich the UE_A10 recognizes a request of the core network_B190.Furthermore, the fifth process may also be a process in which the UE_A10stores the received identification information as a context, or may be aprocess in which the UE transfers the received identificationinformation to a higher layer and/or a lower layer.

In addition, a message transmitted and/or received in thenetwork-initiated session management request may be a PDU SESSIONMODIFICATION COMMAND, may be a PDU SESSION RELEASE COMMAND, but is notlimited thereto.

It should be noted that the UE_A10 may perform identification process ofa congestion management applied by the UE_A10 based on the received 21stidentification information in the fifth process. Here, theidentification process of the congestion management may be the 17thbehavior.

Further, when the UE_A10 receives the 21st identification information,the fifth process may be the 16th behavior. Specifically, it may be, forexample, a process of stopping one or multiple timers running based onthe fourth process described above.

In other words, the UE_A10 receiving the 21st identification informationperforms the 17th behavior to identify a congestion management that isindicated from the network to be stopped or modified, and subsequentlyperforms the 16th behavior to stop or modify the identified congestionmanagement.

Furthermore, each apparatus may, based on the completion of the presentprocedure, perform processing based on identification informationtransmitted and/or received in the present procedure. In other words,the UE_A10 may perform the fifth process based on the completion of thepresent procedure, or may complete the present procedure after thecompletion of the fifth process.

In the above procedure, the core network_B190 can made an indication tothe UE_A10 to stop or modify the congestion management applied by theUE_A10 by the transmission and/or reception of the network-initiatedsession management request message. Furthermore, the UE_A10 can stop ormodify the congestion management applied by the UE_A10 based on thenetwork-initiated session management request message. Here, when theUE_A10 applies one or more congestion managements, the UE_A10 mayidentify the congestion management to be stopped or modified based onthe reception of the identification information included in thenetwork-initiated session management request message from the corenetwork_B190. It should be noted that the applied congestion managementsmay also be different types of congestion managements, and/or congestionmanagements corresponding to different DNNs, and/or congestionmanagements corresponding to different S-NNSAIs, and/or congestionmanagements with different combinations of DNNs and S-NSSAIs.

[1.3.3.2. Example of Second Network-Initiated Session ManagementProcedure]

In the example of first network-initiated session management proceduredescribed in Section 1.3.3.1, it is described that the congestionmanagement is stopped in the procedure regardless of whether thecongestion management applied to the UE_A10 is one of the congestionmanagements from the first congestion management to fourth congestionmanagement.

Without being limited to the above, the procedure described in theexample of first network-initiated session management proceduredescribed in Section 1.3.3.1 may also be a procedure performed accordingto a congestion management. For example, the procedure may be performedfor a congestion management classified into the first congestionmanagement, the third congestion management, or the fourth congestionmanagement among one or more congestion managements applied to UE_A10.

In other words, the UE_A10 may stop the congestion managementcorresponding to the first congestion management, the third congestionmanagement, and/or the fourth congestion management through the fifthprocess.

While the timing of a back-off timer corresponding to the secondcongestion management is performed, the UE_A10 may respond with respectto the core network_B190 without stopping the back-off timercorresponding to the second congestion management if the UE_A10 receivesthe network-initiated session management request message with respect tothe second congestion management.

In other words, while the timing of the back-off timer corresponding toS-NSSAI #A is performed, the UE_A10 may respond with respect to the corenetwork_B190 without stopping the back-off timer corresponding to theS-NSSAI #A when the UE_A10 receives a network-initiated sessionmanagement request message for S-NSSAI #A and any DNN that is beingcongested.

In this way, regarding the second congestion management, in thereception of the network-initiated session management request message,the UE_A10 may transmit a message to the core network_B190 in responseto the network-initiated session management request message, but maycontinue the congestion management. Therefore, the transmission of theUE-initiated session management request message regulated by the secondcongestion management may continue to be suppressed.

Here, as described above, the network-initiated session managementrequest message of the present embodiment may be a PDU SESSIONMODIFICATION COMMAND message in a network-initiated PDU sessionmodification procedure, or may be a PDU SESSION RELEASE COMMAND messagein a network-initiated PDU session release procedure.

Further, as described above, the network-initiated session managementcomplete message for responding with respect to the PDU SESSIONMODIFICATION COMMAND message of the present embodiment may be a PDUSESSION MODIFICATION COMPLETE message, and the network-initiated sessionmanagement complete message for responding with respect to the PDUSESSION RELEASE COMMAND message of the present embodiment may be a PDUSESSION RELEASE COMPLETE message. In addition, when thenetwork-initiated session management request message is a PDU sessionmodification command and/or a PDU session release message, the UE_A10and the core network_B190 may further perform detailed processesdescribed below in addition to the processes described above.

For example, when the core network_B190 transmit a network-initiatedsession management request message including information indicatingReactivation Required, the processing may be performed as follows.Further, the information indicating Reactivation Required is informationindicating a request for activation, and a specific example thereof maybe a 5G session management cause value #39 (5GSM Cause #39).

Hereinafter, a first process and procedure example at the time when theinformation indicating a reactivation request is received will bedescribed.

When the UE_A10 receives a network-initiated session management requestmessage including information indicating Reactivation Required, theUE_A10 does not initiate a UE-initiated PDU session establishmentprocedure again immediately after the completion of thenetwork-initiated session management procedure, but waits for therelease of the congestion management and then initiates a UE-initiatedPDU session establishment procedure again. Here, the UE-initiated PDUsession establishment procedure may be a UE-initiated PDU sessionestablishment procedure for PDU session type, SSC mode, DNN, and S-NSSAIprovided in the UE-initiated PDU establishment procedure when the PDUsession to be changed or released is established.

Further, the waiting for the release of the congestion management may beperformed after the expiration of a timer corresponding to the secondcongestion management. In other words, it may be performed after thecounting of the timer corresponding to the second congestion managementis completed and/or after the timer value corresponding to the secondcongestion management becomes zero.

Also, the UE_A10 may include the following supplementary message in thenetwork-initiated session management compete message.

The supplementary information may be information indicating the waitingfor the expiration of a timer and/or information of a remaining timervalue. Here, the timer may be a timer corresponding to the secondcongestion management. In addition, the waiting for expiration of thetimer may be performed after the timer is expired. In other words, itmay be performed after the counting of the timer corresponding to thesecond congestion management is completed and/or after the timer valuecorresponding to the second congestion management becomes zero.

In addition, the core network_B190 may receive a network-initiatedsession management complete message including the supplementary messageand identify the remaining timer value. Further, the UE-initiated PDUsession establishment procedure may be identified after the timeindicated by the remaining timer value has elapsed.

Here, the remaining timer identified by the core network_B190 may be avalue indicated by the received supplementary information, or may be avalue that takes into account an offset, as compared with the valueindicated by the received supplementary information, between a time atwhich the UE_A10 transmits the network-initiated session managementcompletion message and a time at which the core network_B190 receivesthe message.

In addition, the present invention is not limited to the first processand procedure example at the time when the information indicating thereactivation request is received, and a second process and procedureexample at the time when the information indicating a reactivationrequest is received may be performed as follows.

As described above, with respect to the second congestion management, inthe reception of the network-initiated session management requestmessage, the UE_A10 may transmit a message to the core network_B190 inresponse to the network-initiated session management request message,but may continue the congestion management. Therefore, the transmissionof the UE-initiated session management request message regulated by thesecond congestion management continues to be suppressed, but the UE_A10and/or the core network_B190 may be configured to be allowed for thetransmission as long as a UE-initiated PDU session establishmentprocedure is initiated again.

In other words, when the UE_A10 receives a network-initiated sessionmanagement request message including information indicating ReactivationRequired, the UE_A10 initiates a UE-initiated PDU session establishmentprocedure again after the completion of the network-initiated sessionmanagement procedure. Here, the UE-initiated PDU session establishmentprocedure may be a UE-initiated PDU session establishment procedure forPDU session type, SSC mode, DNN, and S-NSSAI provided in theUE-initiated PDU establishment procedure when the PDU session to bechanged or released is established.

Further, the UE_A10 and the core network_B190 may perform and complete aprocedure allowed as an exception while the UE_A10 continues to applythe congestion management, but the UE_A10 may suppress the initiation ofother UE-initiated session management procedure suppressed by the secondcongestion management.

In addition, the present invention is not limited to the first andsecond process and procedure examples at the time when the informationindicating the reactivation request is received, and a third process andprocedure example at the time when the information indicating areactivation request is received may be performed as follows.

As described above, with respect to the second congestion management, inthe reception of the network-initiated session management requestmessage, the UE_A10 may transmit a message to the core network_B190 inresponse to the network-initiated session management request message.Further, when the UE_A10 receives a network-initiated session managementrequest message including information indicating Reactivation Required,the UE_A10 stops the application of the second congestion management.

In other words, the UE_A10 may continue the congestion management whenthe network-initiated session management request message does notinclude information indicating Reactivation Required. In this case, thetransmission of the UE-initiated session management request messageregulated by the second congestion management is suppressed.

Therefore, when the UE_A10 receives a network-initiated sessionmanagement request message including information indicating ReactivationRequired, the UE_A10 initiates a UE-initiated PDU session establishmentprocedure again after the completion of the network-initiatednetwork-initiated session management procedure. Here, the UE-initiatedPDU session establishment procedure may be a UE-initiated PDU sessionestablishment procedure for PDU session type, SSC mode, DNN, and S-NSSAIprovided in the UE-initiated PDU establishment procedure when themodified or released PDU session is established.

In addition, the present invention is not limited to the first, second,and third process and procedure examples at the time when theinformation indicating the reactivation request is received, and theinformation indicating the reactivation request may be configured not tobe transmitted by the core network_B190 as follows.

More specifically, the core network_B190 may be configured to suppressthe inclusion of information indicating Reactivation Required whentransmitting a network-initiated session management request message tothe UE_A10 to which a congestion management is applied.

Alternatively, the core network_B190 may be configured to suppress theinclusion of information indicating Reactivation Required when the corenetwork_B190 transmits a network-initiated session management requestmessage to the UE_A10 to which a second congestion management isapplied.

The processes and procedures of the UE_A10 and the core network_B190have been described above, but the processes of the core network_B190described in this section may be more specifically a process performedby a control apparatus such as the SMF_A230 and/or the AMF_A240 in thecore network_B190. Therefore, the expression that the core network_B190transmits and receives a control message may mean that a controlapparatus, such as the SMF_A230 and/or the AMF_A240 in the corenetwork_B190, transmits and receives a control message.

In addition, the present invention is not limited to this section. Inthe expressions used in the description of the present embodiment, theprocess of releasing the application of the congestion management or theprocess of stopping the congestion management may include a process ofstopping a back-off timer corresponding to the congestion management,and the process of continuing the application of the congestionmanagement or the process of continuing the congestion management mayinclude continuing the counting of a back-off timer corresponding to thecongestion management.

Further, in the first, second, and third process and procedure examplesdescribed in this section at the time when the information indicating areactivation request is received, the network-initiated sessionmanagement request message and/or the network-initiated sessionmanagement procedure has been described for the UE with respect toS-NSSAI #A and any DNN in congestion.

In other words, the S-NSSAI #A and any DNN in congestion may be S-NSSAI#A and any DNN associated with a PDU session subjected to thenetwork-initiated session management request message and/or thenetwork-initiated session management procedure of this section.

Besides, the UE_A10 and the core network_B190 may perform an anchorrelocation procedure of SSC Mode 2 including the procedure of thissection, and switch to the anchor of a PDU session or a PDU session witha different anchor to continue the communication. Here, the anchorrelocation procedure of SSC mode 2 is a procedure initiated and startedby the core network_B190, and the procedure associated with thetransmission of a PDU session release command performed within thisprocedure is one of the procedures described in this section.

In addition, the UE_A10 and the core network_B190 may perform an anchorrelocation procedure of SSC mode 3 including the procedure of thissection, and switch to the anchor of a PDU session or a PDU session witha different anchor to continue the communication. Here, the anchorrelocation procedure of SSC mode 3 is a procedure initiated and startedby the core network_B190, and the procedure associated with thetransmission of a PDU session modification command performed within thisprocedure is one of the procedures described in this section.

Next, in the state where congestion management is applied, the processat the time when the UE moves with a PLMN changed will be described.

Here, the process at the time when the UE_A10 changes the PLMN in thestate where the first congestion management is applied will beespecially described. Here, the first congestion management and theprocess regulated at the time when the first congestion management isapplied may be as described above.

If the description is repeated, the first congestion management may be aDNN-based congestion management. For example, the first congestionmanagement may be a congestion management applied by the NW to theUE_A10 based on a message rejecting a UE-initiated session managementrequest in a case that the NW receives a UE-initiated session managementrequest using DNN #A from the UE_A10 and the NW detects congestion withrespect to a specific DNN, such as DNN #A. In this case, in theapplication of the first congestion management, the UE_A10 may start thecounting of the back-off timer corresponding to the first congestionmanagement received from the NW, and may not transmit the UE-initiatedsession management request using the DNN #A until the back-off timerexpires. In addition, using DNN may mean including DNN information in aUE-initiated session management request such as a PDU sessionestablishment request message.

Here, the first congestion management for explanation purpose isexpressed as “a first congestion management for a specific DNN”.

In addition, in the first congestion management, even when theUE-initiated session management request does not include DNNinformation, the NW may select a default DNN initiated by the NW andconfigure it as a target subjected to congestion management. In otherwords, the first congestion management may be a congestion managementapplied by the NW to the UE_A10 based on a message rejecting aUE-initiated session management request in a case that the NW receivesfrom the UE_A10 a UE-initiated session management request that does notuse a DNN and the NW detects congestion with respect to a default DNN.In this case, in the application of the first congestion management, theUE_A10 may start the counting of the back-off timer corresponding to thefirst congestion management received from the NW, and may not transmitthe UE-initiated session management request that does not use a DNNuntil the back-off timer expires. In addition, using no DNN may meanthat including no DNN information in a UE-initiated session managementrequest such as a PDU session establishment request message.

Here, for explanation purpose, the first congestion management for thedefault DNN is applied based on a UE-initiated session managementrequest that does not use DNN information and thus is expressed as“congestion management for No DNN” in order to be distinguished from thecongestion management for a specific DNN. Furthermore, the UE-initiatedsession management request such as the PDU session establishment requestmessage that does not use a DNN is expressed as the UE-initiated sessionmanagement request using No DNN. For example, the PDU sessionestablishment request message using No DNN is the PDU sessionestablishment request message that does not use a DNN.

Further, the UE_A10 may be configured to be able to transmit a PDUsession establishment request message using a specific DNN in a new PLMNwhen the UE_A10 performs the counting of a back-off timer correspondingto the first congestion management for the specific DNN in a PLMNchange, or when the back-off timer corresponding to the first congestionmanagement for the specific DNN is deactivated. Therefore, the UE_A10may transmit the PDU session establishment request message using thespecific DNN based on the configuration.

Here, the UE_A10 may continue counting until the timer expires withoutstopping the back-off timer that is counting. Alternatively, the UE_A10may continue to keep the deactivated back-off timer in a deactivatedstate.

Thus, the first congestion management for a specific DNN may alsocorrespond to a PLMN.

For example, when the first congestion management for a specific DNN isapplied, the UE associates the back-off timer with a PLMN and a specificDNN to start counting, and when the back-off timer is zero ordeactivated, a PDU session using the specific DNN associated with theback-off timer may not be established in the PLMN associated with theback-off timer. In addition, when the back-off timer is deactivated, aPDU session using the specific DNN associated with the back-off timermay not be established in the PLMN associated with the back-off timeruntil the terminal power is OFF or the USIM is removed. In addition,when the back-off timer is zero, a PDU session using the specific DNNassociated with the back-off timer may be established in the PLMNassociated with the back-off timer.

In other words, the UE_A10 may be configured to be able to transmit aPDU session establishment request message using a specific DNN in a newPLMN when the UE_A10 performs the counting of a back-off timercorresponding to the first congestion management for the specific DNNand a PLMN before changed in a PLMN change, or when the back-off timercorresponding to the first congestion management for the specific DNNand the PLMN before changed is deactivated, and when the counting of theback-off timer corresponding to the first congestion management for thespecific DNN and a PLMN after changed is not performed, and when theback-off timer corresponding to the first congestion management for thespecific DNN and the PLMN after changed is not deactivated. Further, theUE 10 may transmit a PDU session establishment request message using aspecific DNN based on the configuration.

Further, the UE_A10 may be configured to be able to transmit a PDUsession establishment request message that does not use a DNN in a newPLMN when the UE_A10 performs the counting of a back-off timercorresponding to the first congestion management for No DNN in a PLMNchange, or when the back-off timer corresponding to the first congestionmanagement for No DNN is deactivated. Therefore, the UE_A10 may transmitthe PDU session establishment request message using the specific DNNbased on the configuration.

Here, the UE_A10 may continue counting until the timer expires withoutstopping the back-off timer that is counting. Alternatively, the UE_A10may continue to keep the deactivated back-off timer in a deactivatedstate.

Thus, the first congestion management for No DNN may also correspond toa PLMN. In other words, the UE_A10 may be configured to be able totransmit a PDU session establishment request message without using a DNNin a new PLMN when the UE_A10 performs the counting of a back-off timerof the first congestion management for No DNN corresponding to a PLMNbefore changed in a PLMN change, or when the back-off timer of the firstcongestion management for No DNN corresponding to the PLMN beforechanged is deactivated, and when the counting of the back-off timer ofthe first congestion management for No DNN corresponding to a PLMN afterchanged is not performed, and the back-off timer of the first congestionmanagement for No DNN corresponding to the PLMN is not deactivated.Further, the UE 10 may transmit a PDU session establishment requestmessage that does not use a DNN based on the configuration.

As described above, the UE_A10 may perform the same process regardlessof whether the first congestion management is for a specific DNN or forNo DNN.

In other words, the UE_A10 may be configured to be able to transmit aPDU session establishment request message using a specific DNN and/or aPDU session establishment request message that does not use a DNN, whichare/is regulated by the congestion management corresponding to a PLMNbefore changed, in a new PLMN when the UE_A10 performs the counting of aback-off timer of the first congestion management corresponding to thePLMN before changed in a PLMN change, or when the back-off timer of thefirst congestion management corresponding to the PLMN before changed isdeactivated, and when the counting of the back-off timer of the firstcongestion management corresponding to a PLMN after changed is notperformed, and the back-off timer of the first congestion managementcorresponding to the PLMN is not deactivated.

Alternatively, the UE_A10 may perform a different process depending onwhether the first congestion management is for a specific DNN or for NoDNN.

Further, the UE_A10 may be configured not to transmit a PDU sessionestablishment request message using a specific DNN in a new PLMN whenthe UE_A10 performs the counting of a back-off timer corresponding tothe first congestion management for the specific DNN in a PLMN change,or when the back-off timer corresponding to the first congestionmanagement for the specific DNN is deactivated. Therefore, the UE_A10may regulate the transmission of the PDU session establishment requestmessage using the specific DNN based on the configuration.

Here, the UE_A10 may continue counting until the timer expires withoutstopping the back-off timer that is counting. Alternatively, the UE_A10may continue to keep the deactivated back-off timer in a deactivatedstate.

Thus, the first congestion management for a specific DNN may be appliedto different PLMNs.

On the other hand, the UE_A10 may be configured to be able to transmit aPDU session establishment request message that does not use a DNN in anew PLMN when the UE_A10 performs the counting of a back-off timercorresponding to the first congestion management for No DNN in a PLMNchange, or when the back-off timer corresponding to the first congestionmanagement for No DNN is deactivated. Therefore, the UE_A10 may transmitthe PDU session establishment request message using the specific DNNbased on the configuration.

Here, the UE_A10 may continue counting until the timer expires withoutstopping the back-off timer that is counting. Alternatively, the UE_A10may continue to keep the deactivated back-off timer in a deactivatedstate.

Thus, the first congestion management for No DNN may also correspond toa PLMN.

For example, when the first congestion management for No DNN is applied,the UE associates the back-off timer with a PLMN and No DNN to startcounting, and when the back-off timer is zero or deactivated, a PDUsession using No DNN associated with the back-off timer may not beestablished in the PLMN associated with the back-off timer. In addition,when the back-off timer is deactivated, a PDU session using No DNNassociated with the back-off timer may not be established in the PLMNassociated with the back-off timer until the terminal power is OFF orthe USIM is removed. In addition, when the back-off timer is zero, a PDUsession using No DNN associated with the back-off timer may beestablished in the PLMN associated with the back-off timer.

In other words, the UE_A10 may be configured to be able to transmit aPDU session establishment request message without using a DNN in a newPLMN when the UE_A10 performs the counting of a back-off timer of thefirst congestion management for No DNN corresponding to a PLMN beforechanged in a PLMN change, or when the back-off timer of the firstcongestion management for No DNN corresponding to the PLMN beforechanged is deactivated, and when the counting of the back-off timer ofthe first congestion management for No DNN corresponding to a PLMN afterchanged is not performed, and the back-off timer of the first congestionmanagement for No DNN corresponding to the PLMN is not deactivated.Further, the UE 10 may transmit a PDU session establishment requestmessage that does not use a DNN based on the configuration.

Here, whether the first congestion management performs the same processfor a specific DNN or No DNN or performs a different process as theprocess associated with a PLMN change may be configured based oninformation configured in advance in the UE_A10, but may be determinedbased on whether the second PLMN after being changed is an equivalentPLMN to the first PLMN before being changed. For example, when thesecond PLMN after being changed is not an equivalent PLMN to the firstPLMN before being changed, the same process may also be applied. Whenthe second PLMN after being changed is an equivalent PLMN to the firstPLMN before being changed, a different process may also be performed.

Besides, in the present embodiment, the deactivation of the back-offtimer may mean that the congestion management associated with theback-off timer and/or the back-off timer has transitioned to adeactivated state. When the UE_A10 receives a timer value indicating thedeactivation, the UE_A10 may deactivate the back-off timer and/or thecongestion management corresponding to the back-off timer.

Here, the deactivated back-off timer and/or the deactivated congestionmanagement corresponding to the back-off timer may correspond to one ormore of the first to fourth types of congestion managements. Which typeof congestion management corresponding to the deactivated back-off timerand/or the deactivated congestion management corresponding to theback-off timer may be similarly determined and identified when theback-off timer value is received.

More specifically, the UE_A10 may receive from the NW the 14thidentification information and the 15th identification informationindicating the deactivation of the back-off timer and/or the congestionmanagement corresponding to the back-off timer, and deactivate theback-off timer for the type of congestion management indicated by the15th identification information.

In addition, in the state where the back-off timer and/or the congestionmanagement is deactivated, the application of the congestion managementmay be continued until the terminal power is turned off or the USIM isremoved. Further, the process to be regulated at this time may be thesame as a process to be regulated when the back-off timer is countedaccording to the type of congestion management.

The processes of the UE_A10 and the NW associated with the PLMN changedescribed above have been described for the first congestion managementand/or the back-off timer for the first congestion management, but thesame process may also be performed for the second congestion management,the third congestion management, and the fourth congestion management.However, the PDU session establishment request message of which thetransmission is regulated or allowed may be a message corresponding toeach type. In other words, the congestion management and/or the back-offtimer corresponding to the congestion management may also correspond toa PLMN regardless of the type of congestion management. Alternatively,the congestion management and/or the back-off timer corresponding to thecongestion management may also correspond to a PLMN regardless of thetype of congestion management. Therefore, for the first congestionmanagement, the second congestion management, and the third congestionmanagement, the congestion management and/or the back-off timercorresponding to the congestion management may be configured tocorrespond to a PLMN. Therefore, for the first congestion management forNo DNN, the second congestion management for No DNN, and the thirdcongestion management for No DNN, the congestion management and/or theback-off timer corresponding to the congestion management may beconfigured to correspond to a PLMN, and the first congestion managementfor a particular DNN may not correspond to the PLMN. In addition, theprocess at the time when each congestion management corresponds to thePLMN and/or the process related to the back-off timer corresponding toeach congestion management may be the process for the first congestionmanagement associated with the PLMN as described above, and/or the firstcongestion management in the description of the process related to theback-off timer corresponding to the first congestion managementcorresponding to the PLMN described above may be replaced by each typeof the congestion management from the second to fourth congestionmanagements. In addition, the process at the time when each congestionmanagement does not correspond to the PLMN and/or the process related tothe back-off timer corresponding to each congestion management may bethe process for the first congestion management that does not correspondto the PLMN as described above, and/or the first congestion managementin the description of the process related to the back-off timercorresponding to the first congestion management that does notcorrespond to PLMN as described above may be replaced by each type ofthe congestion management from the second to fourth congestionmanagements. However, as described above, the PDU session establishmentrequest message of which the transmission is regulated or allowed may bea message corresponding to each type.

In addition, in the description of the present embodiment, when it isexpressed that an NW performs transmission to a UE_A10, it may mean thatan AMF or an SMF performs transmission to a UE_A10, and when it isexpressed that a UE_A10 performs transmission to an NW, it may mean thata UE_A10 performs transmission to an AMF or an SMF. Further, when it isexpressed that an NW performs reception from a UE_A10, it may mean thatan AMF or an SMF performs reception from a UE_A10, and when it isexpressed that a UE_A10 performs reception from an NW, it may mean thata UE_A10 performs reception from an AMF or an SMF.

[1.4 Modified Example of Fourth Process]

In the present embodiment, although the fourth process example has beendescribed, it is not limited to the previous description, and thefollowing process may be performed in the fourth process.

This modified example is mainly related to the behavior of theregistration procedure illustrated in FIG. 10 and/or the PDU sessionestablishment registration procedure illustrated in FIG. 11. Further,the present embodiment relates to a case that the PDU sessionestablishment reject message (S1122) received by the UE_A includes the15th identification information and/or 14th identification informationand/or 11th identification information in the PDU session establishmentprocedure shown in the FIG. 11.

It should be noted that, in the present modified example, the 15thidentification information is information indicating one or more causevalues notified by the NW to the UE for the rejection of the presentprocedure for a cause other than the application of a congestionmanagement. The 14th identification information is informationindicating a value of the back-off timer. The 11th identificationinformation is information indicating re-attempt information. Theback-off timer may be the first timer used in the third congestionmanagement described above in the present embodiment and is not limitedthereto as long as it is a timer of the communication system that can berecognized by the UE. It should be noted that, in order to distinguishthe back-off timer from the first timer described above, an SM back-offtimer is expressed. In addition, when the PDU session establishmentprocedure does not include DNN information, “no DNN” is expressed inorder to be distinguished from a control signal management with DNNinformation included. In addition, similarly, when the PDU sessionestablishment procedure does not include S-NSSAI information, “noS-NSSAI” is expressed in order to be distinguished from a control signalmanagement with S-NSSAI information included.

The fourth process (S1124) may be performed according to contents of the11th identification information and/or the 14th identificationinformation and/or the 15th identification information included in thePDU session establishment reject message received by the UE_A.

The SMF_A230 or the AMF_A240 may load an SM back-off timer indicated bythe 14th identification information and transmit the PDU sessionestablishment reject message (S1122) to the UE_A10 when a reject causevalue indicated by the 15th identification information is other thaninsufficient resources and/or insufficient resources for specific sliceand DNN and/or insufficient resources for specific slice.

In this case, the UE_A10 may perform the fourth process based on thereceived SM back-off timer value when the reject cause value indicatedby the 15th identification information is other than insufficientresources and/or insufficient resources for specific slices and DNNand/or insufficient resources for specific slices and/or userauthentication or authorization failed and/or out of LADN service areaand/or PDU session type IPv4 only allowed and/or PDU session type IPv6only allowed and/or PDU session does not exist.

Specifically, the UE_A10 may perform a first process example describedbelow as the fourth process example of the present modified example whenthe SM back-off timer value is not zero or invalid.

UE_A10 may start the SM back-off timer for the PLMN and/or the DNNand/or the S-NSSAI, may also start the SM back-off timer for the PLMNand/or the no DNN and/or the S-NSSAI, may also start the SM back-offtimer for the PLMN and/or the DNN and/or the no S-NSSAI, and may alsostart the SM back-off timer for the PLMN and/or the no DNN and/or the noS-NSSAI.

In addition, the UE_A10 may suppress the transmission of the PDU sessionestablishment request message (1011) based on the SM back-off timervalue.

Specifically, the UE_A10 may suppress the reconnection using another PDUsession establishment request message directed to DNN and S-NSSAIparameters transmitted in the PDU session establishment request message(1011) until the SM back-off timer for PLMN and/or DNN and/or S-NSSAIexpires, and/or until the terminal power is turned on/off, or until theUSIM (Universal Subscriber Identity Module) is inserted/removed.

In addition, the UE_A10 may suppress the reconnection using another PDUsession establishment request message directed to no DNN and S-NSSAIparameters transmitted in the PDU session establishment request message(1011) until the SM back-off timer for PLMN and/or no DNN and/or S-NSSAIexpires, and/or until the terminal power is turned on/off, or until theUSIM (Universal Subscriber Identity Module) is inserted/removed.

In addition, the UE_A10 may suppress the reconnection using another PDUsession establishment request message directed to DNN and no S-NSSAIparameters transmitted in the PDU session establishment request message(1011) until the SM back-off timer for PLMN and/or DNN and/or no S-NSSAIexpires, and/or until the terminal power is turned on/off, or until theUSIM (Universal Subscriber Identity Module) is inserted/removed.

In addition, the UE_A10 may suppress the reconnection using another PDUsession establishment request message directed to no DNN and no S-NSSAIparameters transmitted in the PDU session establishment request message(1011) until the SM back-off timer for PLMN and/or no DNN and/or noS-NSSAI expires, and/or until the terminal power is turned on/off, oruntil the USIM (Universal Subscriber Identity Module) isinserted/removed.

Further, the UE_A10 may perform a second process example different fromthe first process example as the fourth process example of the presentmodified example when the SM back-off timer value indicates invalidity.

The UE_A10 may suppress the reconnection using another PDU sessionestablishment request message directed to DNN and S-NSSAI parameterstransmitted in the PDU session establishment request message (1011)until the terminal power is turned on/off, or until the USIM (UniversalSubscriber Identity Module) is inserted/removed.

In addition, the UE_A10 may suppress the reconnection using another PDUsession establishment request message directed to no DNN and S-NSSAIparameters transmitted in the PDU session establishment request message(1011) until the terminal power is turned on/off, or until the USIM(Universal Subscriber Identity Module) is inserted/removed.

In addition, the UE_A10 may suppress the reconnection using another PDUsession establishment request message directed to DNN and no S-NSSAIparameters transmitted in the PDU session establishment request message(1011) until the terminal power is turned on/off, or until the USIM(Universal Subscriber Identity Module) is inserted/removed.

In addition, the UE_A10 may suppress the reconnection using another PDUsession establishment request message directed of no DNN and no S-NSSAIparameters transmitted in the PDU session establishment request message(1011) until the terminal power is turned on/off, or until the USIM(Universal Subscriber Identity Module) is inserted/removed.

Further, the UE_A10 may perform a third process example different fromthe first and second process examples as the fourth process example ofthe present modified example when the SM back-off timer value indicateszero.

The UE_A10 may stop if the SM back-off timer corresponding to DNN andS-NSSAI transmitted in the PDU session establishment request message(1011) is activated, and transmit another PDU session establishmentrequest message using DNN and S-NSSAI transmitted in the PDU sessionestablishment request message (1011).

In addition, the UE_A10 may stop if the SM back-off timer correspondingto no DNN and S-NSSAI transmitted in the PDU session establishmentrequest message (1011) is started, and transmit another PDU sessionestablishment request message using no DNN and S-NSSAI transmitted inthe PDU session establishment request message (1011).

In addition, the UE_A10 may stop if the SM back-off timer correspondingto DNN and no S-NSSAI transmitted in the PDU session establishmentrequest message (1011) is started, and transmit another PDU sessionestablishment request message using DNN and no S-NSSAI transmitted inthe PDU session establishment request message (1011).

In addition, the UE_A10 may stop if the SM back-off timer correspondingto no DNN and no S-NSSAI transmitted in the PDU session establishmentrequest message (1011) is activated, and transmit another PDU sessionestablishment request message using no DNN and no S-NSSAI transmitted inthe PDU session establishment request message (1011).

It should be noted that UE_A10 does not stop the activated SM back-offtimer when the PLMN is changed or when a change from an N1 mode to an S1mode occurs. This is because, for example, when the PLMN change returnsto the original PLMN again from the PLMN change destination, theback-off timer activated by the original PLMN continues to be activated,and the control signal management applied to the original PLMN continuesto be applied.

Further, the UE_A10 may perform the fourth procedure example as thefourth process example of the present modified example when a PLMNchange is performed while the SM back-off timer started before the PLMNchange is started. Here, the PLMN before changed is referred to as theoriginal PLMN.

The UE_A10 may transmit a PDU session establishment request messageusing the same S-NSSAI and DNN as the S-NSSAI and DNN corresponding tothe SM back-off timer activated by the original PLMN when the SMback-off timer activated by the original PLMN for the S-NSSAI and DNN isnot activated at the PLMN change destination.

In addition, the UE_A10 may transmit a PDU session establishment requestmessage using the same S-NSSAI and no DNN as the S-NSSAI and no DNNcorresponding to the SM back-off timer activated by the original PLMNwhen the SM back-off timer activated by the original PLMN for theS-NSSAI and no DNN is not activated at the PLMN change destination.

In addition, the UE_A10 may transmit a PDU session establishment requestmessage using the same no S-NSSAI and DNN as the no S-NSSAI and DNNcorresponding to the SM back-off timer activated by the original PLMNwhen the SM back-off timer activated by the original PLMN for the noS-NSSAI and DNN is not activated at the PLMN change destination.

In addition, the UE_A10 may transmit a PDU session establishment requestmessage using the same no S-NSSAI and no DNN as the no S-NSSAI and noDNN corresponding to the SM back-off timer activated by the originalPLMN when the SM back-off timer activated by the original PLMN for theno S-NSSAI and no DNN is not activated at the PLMN change destination.

Further, the UE_A10 may perform a fifth procedure example different fromthe first, second, and third procedure examples as the fourth processexample of the present modified example when the cause value indicatedby the 15th identification information is “user authentication orauthentication failed”, or “PDU session type IPv4 only allowed”, or “PDUsession type IPv6 only allowed”.

Specifically, the fifth procedure example may be a procedure that theUE_A10 may not automatically transmit the reconnection using another PDUsession establishment request message directed to DNN and S-NSSAIparameters transmitted in the PDU session establishment request message(1011) until the PDU session type used in the PDU session establishmentrequest message (1011) is changed, or until the terminal power ison/off, or until the USIM (Universal Subscriber Identity Module) isinserted/removed.

In addition, it may be a procedure that the UE_A10 may not automaticallytransmit the reconnection using another PDU session establishmentrequest message directed to no DNN and S-NSSAI parameters transmitted inthe PDU session establishment request message (1011) until the PDUsession type used in the PDU session establishment request message(1011) is changed, or until the terminal power is on/off, or until theUSIM (Universal Subscriber Identity Module) is inserted/removed.

In addition, it may be a procedure that the UE_A10 may not automaticallytransmit the reconnection using another PDU session establishmentrequest message directed to DNN and no S-NSSAI parameters transmitted inthe PDU session establishment request message (1011) until the PDUsession type used in the PDU session establishment request message(1011) is changed, or until the terminal power is on/off, or until theUSIM (Universal Subscriber Identity Module) is inserted/removed.

In addition, it may be a procedure that the UE_A10 may not automaticallytransmit the reconnection using another PDU session establishmentrequest message directed to no DNN and no S-NSSAI parameters transmittedin the PDU session establishment request message (1011) until the PDUsession type used in the PDU session establishment request message(1011) is changed, or until the terminal power is on/off, or until theUSIM (Universal Subscriber Identity Module) is inserted/removed.

Further, the UE_A10 may perform a sixth procedure example different fromthe first, second, third, and fifth procedure examples as the fourthprocess example of the present modified example when the cause valueindicated by the 15th identification information is “PDU session doesnot exist”.

Specifically, the UE_A10 may transmit an initial PDU sessionestablishment request (initial request) message directed to DNN andS-NSSAI parameters transmitted in the PDU session establishment requestmessage (1011).

In addition, the UE_A10 may transmit an initial PDU sessionestablishment request (initial request) message directed to no DNN andS-NSSAI parameters transmitted in the PDU session establishment requestmessage (1011).

In addition, the UE_A10 may transmit an initial PDU sessionestablishment request (initial request) message directed to DNN and noS-NSSAI parameters transmitted in the PDU session establishment requestmessage (1011).

In addition, the UE_A10 may transmit an initial PDU sessionestablishment request (initial request) message directed to no DNN andno S-NSSAI parameters transmitted in the PDU session establishmentrequest message (1011).

Further, the UE_A10 may perform a seventh procedure example differentfrom the first, second, third, fifth, and sixth procedure examples asthe fourth process example of the present modified example when thecause value indicated by the 15th identification information is “userauthentication or authentication failed”, and/or “PDU session type IPv4only allowed”, and/or “PDU session type IPv6 only allowed”, and/or “PDUsession does not exit”.

Specifically, the UE_A10 may also ignore the received SM back-off timer.

Further, the UE_A10 may transmit another PDU session establishmentrequest message based on the re-attempt information indicated in the11th identification information. Specifically, when the connection in anequivalent PLMN is allowed in the re-attempt information, the UE_A10 maytransmit another PDU session establishment request message directed toDNN and S-NSSAI parameters transmitted in the PDU session establishmentrequest message (1011) in the equivalent PLMN.

In addition, when the connection in an equivalent PLMN is allowed in there-attempt information, the UE_A10 may transmit another PDU sessionestablishment request message directed to no DNN and S-NSSAI parameterstransmitted in the PDU session establishment request message (1011) inthe equivalent PLMN.

In addition, when the connection in an equivalent PLMN is allowed in there-attempt information, the UE_A10 may transmit another PDU sessionestablishment request message directed to DNN and no S-NSSAI parameterstransmitted in the PDU session establishment request message (1011) inthe equivalent PLMN.

In addition, when the connection in an equivalent PLMN is allowed in there-attempt information, the UE_A10 may transmit another PDU sessionestablishment request message directed to no DNN and no S-NSSAIparameters transmitted in the PDU session establishment request message(1011) in the equivalent PLMN. As described above, the UE_A10 may alsoperform a process based on the reception of a PDU session establishmentreject message.

In other words, the process based on the reception of a PDU sessionestablishment reject message may be a process example described below.In addition, the process example may be a process performed when the PDUsession establishment rejection message includes a timer value.

When a 5GSM cause value included in the PDU session establishment rejectmessage indicates a cause value other than another cause value relatedto congestion management, the UE_A10 may start a back-off timer for acombination of PLMN, DNN, and S-NSSAI by using a received timer valuebased on a received 5GSM cause value.

Here, the DNN and the S-NSSAI may be indicated by UE_A10. Specifically,as described above so far, the UE_A10 may also include the DNN and theS-NSSAI in a PDU session establishment request message. In addition, thePDU session establishment reject message in the present process may be aresponse message to the PDU session establishment request message.

Further, the cause value related to the congestion management may be acause value indicating insufficient resources and/or insufficientresources for a specific slice and/or insufficient resources for aspecific slice and a DNN.

In other words for the above process example, when the 5GSM cause valueincluded in the PDU session establishment reject message is differentfrom the cause value included in the following cause value group, theUE_A10 may start a back-off timer with respect to a combination of PLMN,DNN, and S-NSSAI by using a received timer value.

Here, the cause value group may be the aforementioned cause valuerelated to congestion management, and/or user authentication orauthorization failed and/or out of LADN service area, and/or PDU sessiontype IPv4 only allowed and/or PDU session type IPv6 only allowed and/orPDU session does not exist.

Specifically, when a 5GSM cause value included in the PDU sessionestablishment reject message indicates request rejected unspecified, theUE_A10 may start a back-off timer with respect to a combination of PLMN,DNN, and S-NSSAI by using a received timer value.

Further, the process performed by the UE_A10 during the counting of theback-off timer described above may be the process already described inthis section.

2. Modified Example

The program running in the apparatuses according to the presentinvention may be a program that controls a central processing unit (CPU)to operate a computer so as to implement the functions of the embodimentaccording to the present invention. Programs or information processed bythe programs are temporarily stored in a volatile memory such as arandom access memory (RAM), a non-volatile memory such as a flashmemory, a hard disk drive (HDD), or other storage device system.

Besides, a program for implementing such functions of the embodimentaccording to the present invention may be recorded on acomputer-readable recording medium. It may be implemented by loading theprogram recorded on the recording medium into a computer system andexecuting the program. The “computer system” described herein refers toa computer system built into the apparatuses, and includes an operatingsystem and hardware components such as peripheral devices. In addition,the “computer-readable recording medium” may be any of a semiconductorrecording medium, an optical recording medium, a magnetic recordingmedium, a medium dynamically retaining the program for a short time, orany other computer readable recording medium.

In addition, the various functional blocks or various features of theapparatuses used in the above-mentioned embodiments may be installed orperformed by a circuit, such as an integrated circuit or multipleintegrated circuits. Circuits designed to execute the functionsdescribed in the present description may include general-purposeprocessors, digital signal processors (DSPs), application specificintegrated circuits (ASICs), field programmable gate arrays (FPGAs) orother programmable logic devices, discrete gates or transistor logic,discrete hardware components, or any combination of the above. Thegeneral-purpose processor may be a microprocessor, or may be aconventional processor, controller, microcontroller, or state machine.The above-mentioned circuit may include a digital circuit, or mayinclude an analog circuit. In addition, in a case that with advances insemiconductor technology, a new circuit integration technology mayappear to replace the present technology for integrated circuits, one ormore aspects of the present invention may also use a new integratedcircuit based on the new circuit integration technology.

The present invention is not limited to the above-described embodiments.In the embodiments, apparatuses have been described as an example, butthe invention of the present application is not limited to theseapparatuses, and is applicable to a terminal apparatus or acommunication apparatus of a fixed-type or a stationary-type electronicapparatus installed indoors or outdoors, for example, an AV apparatus, akitchen apparatus, a cleaning or washing machine, an air-conditioningapparatus, office equipment, a vending machine, and other householdapparatuses.

The embodiments of the present invention have been described in detailwith reference to the accompanying drawings, but the specificconfiguration is not limited to the present embodiments and includesdesign modification and the like without departing from the scope of thepresent invention. In addition, various modifications within the scopepresented by the claims may be made to the present invention, andembodiments obtained by suitably combining technical means disclosed bythe different embodiments may also be included in the technical scope ofthe present invention. In addition, a configuration in which constituentelements, described in the respective embodiments and having mutuallythe same effects, are substituted for one another may also be includedin the technical scope of the present invention.

1-4. (canceled)
 5. A method for a user equipment (UE) performing controlsignal management, comprising: transmitting a first initial ProtocolData Unit (PDU) session establishment request message containing arequest type field to a network node to establish a first PDU sessionwith a Data Network Name (DNN) and a Single Network Slice SelectionAssistance Information (S-NSSAI); receiving a PDU session establishmentreject message; setting a request type field contained within a secondinitial PDU session establishment request message to initial request toestablish a second PDU session based on a cause value of the PDU sessionestablishment reject message indicating the first PDU session does notexist; and transmitting the second initial PDU session establishmentrequest message to the network node to establish the second PDU session.6. The method of claim 5, wherein the second PDU session is associatedwith the DNN and the S-NSSAI when the DNN and the S-NSSAI are indicatedin the second initial PDU session establishment request message.
 7. Themethod of claim 5, wherein the second PDU session is associated with theS-NSSAI but not the DNN when no DNN is indicated in the second initialPDU session establishment request message.
 8. The method of claim 5,wherein the second PDU session is associated with the DNN but not theS-NSSAI when no S-NSSAI is indicated in the second initial PDU sessionestablishment request message.
 9. The method of claim 5, wherein thesecond PDU session is not associated with the DNN and not associatedwith the S-NSSAI when no DNN and no S-NSSAI are indicated in the secondinitial PDU session establishment request message.
 10. The method ofclaim 5, wherein the cause value is a 5G Session Management (5GSM) causevalue.
 11. A user equipment (UE) performing control signal management,comprising: a transmission circuitry unit configured to: transmit afirst initial Protocol Data Unit (PDU) session establishment requestmessage containing a request type field to a network node to establish afirst PDU session with a Data Network Name (DNN) and a Single NetworkSlice Selection Assistance Information (S-NSSAI); a reception circuitryunit configured to: receive a PDU session establishment reject message;and the transmission circuitry unit further configured to: set a requesttype field contained within a second initial PDU session establishmentrequest message to initial request to establish a second PDU sessionbased on a cause value of the PDU session establishment reject messageindicating the first PDU session does not exist; and transmit the secondinitial PDU session establishment request message to the network node toestablish the second PDU session.
 12. The UE of claim 11, wherein thesecond PDU session is associated with the DNN and the S-NSSAI when theDNN and the S-NSSAI are indicated in the second initial PDU sessionestablishment request message.
 13. The UE of claim 11, wherein thesecond PDU session is associated with the S-NSSAI but not the DNN whenno DNN is indicated in the second initial PDU session establishmentrequest message.
 14. The UE of claim 11, wherein the second PDU sessionis associated with the DNN but not the S-NSSAI when no S-NSSAI isindicated in the second initial PDU session establishment requestmessage.
 15. The UE of claim 11, wherein the second PDU session is notassociated with the DNN and not associated with the S-NSSAI when no DNNand no S-NSSAI are indicated in the second initial PDU sessionestablishment request message.
 16. The UE of claim 11, wherein the causevalue is a 5G Session Management (5GSM) cause value.
 17. A method for anetwork node performing control signal management, comprising:receiving, from a user equipment (UE), a first initial Protocol DataUnit (PDU) session establishment request message containing a requesttype field to establish a first PDU session with a Data Network Name(DNN) and a Single Network Slice Selection Assistance Information(S-NSSAI); determining whether the first PDU session exists based on atleast one of the DNN and the S-NSSAI; and transmitting, to the UE, a PDUsession establishment reject message with a cause value indicating thefirst PDU session does not exist when the first PDU session isdetermined to not exist.
 18. The method of claim 17, further comprising:receiving, from the UE, a second initial PDU session establishmentrequest message to establish a second PDU session; wherein a requesttype field contained within the second initial PDU session establishmentrequest message is set to initial request to establish a second PDUsession.
 19. The method of claim 18, wherein the second PDU session isassociated with the DNN and the S-NSSAI when the DNN and the S-NSSAI areindicated in the second initial PDU session establishment requestmessage.
 20. The method of claim 18, wherein the second PDU session isassociated with the S-NSSAI but not the DNN when no DNN is indicated inthe second initial PDU session establishment request message.
 21. Themethod of claim 18, wherein the second PDU session is associated withthe DNN but not the S-NSSAI when no S-NSSAI is indicated in the secondinitial PDU session establishment request message.
 22. The method ofclaim 18, wherein the second PDU session is not associated with the DNNand not associated with the S-NSSAI when no DNN and no S-NSSAI areindicated in the second initial PDU session establishment requestmessage.
 23. The method of claim 17, wherein the cause value is a 5GSession Management (5GSM) cause value.